diff --git a/src/modules/core/core.controller.ts b/src/modules/core/core.controller.ts
index a0ad97d..165848c 100644
--- a/src/modules/core/core.controller.ts
+++ b/src/modules/core/core.controller.ts
@@ -2,6 +2,8 @@ import { Response, NextFunction } from 'express';
 import { z } from 'zod';
 import { currenciesService, CreateCurrencyDto, UpdateCurrencyDto } from './currencies.service.js';
 import { countriesService } from './countries.service.js';
+import { statesService, CreateStateDto, UpdateStateDto } from './states.service.js';
+import { currencyRatesService, CreateCurrencyRateDto, ConvertCurrencyDto } from './currency-rates.service.js';
 import { uomService, CreateUomDto, UpdateUomDto } from './uom.service.js';
 import { productCategoriesService, CreateProductCategoryDto, UpdateProductCategoryDto } from './product-categories.service.js';
 import { paymentTermsService, CreatePaymentTermDto, UpdatePaymentTermDto } from './payment-terms.service.js';
@@ -192,6 +194,55 @@ const applyDiscountsSchema = z.object({
   isFirstPurchase: z.boolean().optional(),
 });
 
+// States Schemas
+const createStateSchema = z.object({
+  country_id: z.string().uuid().optional(),
+  countryId: z.string().uuid().optional(),
+  code: z.string().min(1).max(10).toUpperCase(),
+  name: z.string().min(1).max(255),
+  timezone: z.string().max(50).optional(),
+  is_active: z.boolean().optional(),
+  isActive: z.boolean().optional(),
+}).refine((data) => data.country_id !== undefined || data.countryId !== undefined, {
+  message: 'country_id or countryId is required',
+});
+
+const updateStateSchema = z.object({
+  name: z.string().min(1).max(255).optional(),
+  timezone: z.string().max(50).optional().nullable(),
+  is_active: z.boolean().optional(),
+  isActive: z.boolean().optional(),
+});
+
+// Currency Rates Schemas
+const createCurrencyRateSchema = z.object({
+  from_currency_code: z.string().length(3).toUpperCase().optional(),
+  fromCurrencyCode: z.string().length(3).toUpperCase().optional(),
+  to_currency_code: z.string().length(3).toUpperCase().optional(),
+  toCurrencyCode: z.string().length(3).toUpperCase().optional(),
+  rate: z.number().positive(),
+  rate_date: z.string().optional(),
+  rateDate: z.string().optional(),
+  source: z.enum(['manual', 'banxico', 'xe', 'openexchange']).optional(),
+}).refine((data) => data.from_currency_code !== undefined || data.fromCurrencyCode !== undefined, {
+  message: 'from_currency_code or fromCurrencyCode is required',
+}).refine((data) => data.to_currency_code !== undefined || data.toCurrencyCode !== undefined, {
+  message: 'to_currency_code or toCurrencyCode is required',
+});
+
+const convertCurrencySchema = z.object({
+  amount: z.number().min(0),
+  from_currency_code: z.string().length(3).toUpperCase().optional(),
+  fromCurrencyCode: z.string().length(3).toUpperCase().optional(),
+  to_currency_code: z.string().length(3).toUpperCase().optional(),
+  toCurrencyCode: z.string().length(3).toUpperCase().optional(),
+  date: z.string().optional(),
+}).refine((data) => data.from_currency_code !== undefined || data.fromCurrencyCode !== undefined, {
+  message: 'from_currency_code or fromCurrencyCode is required',
+}).refine((data) => data.to_currency_code !== undefined || data.toCurrencyCode !== undefined, {
+  message: 'to_currency_code or toCurrencyCode is required',
+});
+
 class CoreController {
   // ========== CURRENCIES ==========
   async getCurrencies(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
@@ -260,6 +311,261 @@ class CoreController {
     }
   }
 
+  // ========== STATES ==========
+  async getStates(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const filter = {
+        countryId: req.query.country_id as string | undefined,
+        countryCode: req.query.country_code as string | undefined,
+        isActive: req.query.active === 'true' ? true : undefined,
+      };
+      const states = await statesService.findAll(filter);
+      res.json({ success: true, data: states });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async getState(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const state = await statesService.findById(req.params.id);
+      res.json({ success: true, data: state });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async getStatesByCountry(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const states = await statesService.findByCountry(req.params.countryId);
+      res.json({ success: true, data: states });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async getStatesByCountryCode(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const states = await statesService.findByCountryCode(req.params.countryCode);
+      res.json({ success: true, data: states });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async createState(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const parseResult = createStateSchema.safeParse(req.body);
+      if (!parseResult.success) {
+        throw new ValidationError('Datos de estado inválidos', parseResult.error.errors);
+      }
+      const data = parseResult.data;
+      const dto: CreateStateDto = {
+        countryId: data.country_id ?? data.countryId!,
+        code: data.code,
+        name: data.name,
+        timezone: data.timezone,
+        isActive: data.is_active ?? data.isActive,
+      };
+      const state = await statesService.create(dto);
+      res.status(201).json({ success: true, data: state, message: 'Estado creado exitosamente' });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async updateState(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const parseResult = updateStateSchema.safeParse(req.body);
+      if (!parseResult.success) {
+        throw new ValidationError('Datos de estado inválidos', parseResult.error.errors);
+      }
+      const data = parseResult.data;
+      const dto: UpdateStateDto = {
+        name: data.name,
+        timezone: data.timezone ?? undefined,
+        isActive: data.is_active ?? data.isActive,
+      };
+      const state = await statesService.update(req.params.id, dto);
+      res.json({ success: true, data: state, message: 'Estado actualizado exitosamente' });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async deleteState(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      await statesService.delete(req.params.id);
+      res.json({ success: true, message: 'Estado eliminado exitosamente' });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  // ========== CURRENCY RATES ==========
+  async getCurrencyRates(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const filter = {
+        tenantId: req.tenantId,
+        fromCurrencyCode: req.query.from as string | undefined,
+        toCurrencyCode: req.query.to as string | undefined,
+        limit: req.query.limit ? parseInt(req.query.limit as string, 10) : 100,
+      };
+      const rates = await currencyRatesService.findAll(filter);
+      res.json({ success: true, data: rates });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async getCurrencyRate(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const rate = await currencyRatesService.findById(req.params.id);
+      res.json({ success: true, data: rate });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async getLatestRate(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const fromCode = req.params.from.toUpperCase();
+      const toCode = req.params.to.toUpperCase();
+      const dateStr = req.query.date as string | undefined;
+      const date = dateStr ? new Date(dateStr) : new Date();
+
+      const rate = await currencyRatesService.getRate(fromCode, toCode, date, req.tenantId);
+
+      if (rate === null) {
+        res.status(404).json({
+          success: false,
+          message: `No se encontró tipo de cambio para ${fromCode}/${toCode}`
+        });
+        return;
+      }
+
+      res.json({
+        success: true,
+        data: {
+          from: fromCode,
+          to: toCode,
+          rate,
+          date: date.toISOString().split('T')[0]
+        }
+      });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async createCurrencyRate(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const parseResult = createCurrencyRateSchema.safeParse(req.body);
+      if (!parseResult.success) {
+        throw new ValidationError('Datos de tipo de cambio inválidos', parseResult.error.errors);
+      }
+      const data = parseResult.data;
+      const dto: CreateCurrencyRateDto = {
+        tenantId: req.tenantId,
+        fromCurrencyCode: data.from_currency_code ?? data.fromCurrencyCode!,
+        toCurrencyCode: data.to_currency_code ?? data.toCurrencyCode!,
+        rate: data.rate,
+        rateDate: data.rate_date ?? data.rateDate ? new Date(data.rate_date ?? data.rateDate!) : new Date(),
+        source: data.source,
+        createdBy: req.user?.userId,
+      };
+      const rate = await currencyRatesService.create(dto);
+      res.status(201).json({ success: true, data: rate, message: 'Tipo de cambio creado exitosamente' });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async convertCurrency(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const parseResult = convertCurrencySchema.safeParse(req.body);
+      if (!parseResult.success) {
+        throw new ValidationError('Datos de conversión inválidos', parseResult.error.errors);
+      }
+      const data = parseResult.data;
+      const dto: ConvertCurrencyDto = {
+        amount: data.amount,
+        fromCurrencyCode: data.from_currency_code ?? data.fromCurrencyCode!,
+        toCurrencyCode: data.to_currency_code ?? data.toCurrencyCode!,
+        date: data.date ? new Date(data.date) : new Date(),
+        tenantId: req.tenantId,
+      };
+      const result = await currencyRatesService.convert(dto);
+
+      if (result === null) {
+        res.status(404).json({
+          success: false,
+          message: `No se encontró tipo de cambio para ${dto.fromCurrencyCode}/${dto.toCurrencyCode}`
+        });
+        return;
+      }
+
+      res.json({
+        success: true,
+        data: {
+          originalAmount: dto.amount,
+          convertedAmount: result.amount,
+          rate: result.rate,
+          from: dto.fromCurrencyCode,
+          to: dto.toCurrencyCode,
+        }
+      });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async deleteCurrencyRate(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      await currencyRatesService.delete(req.params.id);
+      res.json({ success: true, message: 'Tipo de cambio eliminado exitosamente' });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async getCurrencyRateHistory(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const fromCode = req.params.from.toUpperCase();
+      const toCode = req.params.to.toUpperCase();
+      const days = req.query.days ? parseInt(req.query.days as string, 10) : 30;
+
+      const history = await currencyRatesService.getHistory(fromCode, toCode, days, req.tenantId);
+      res.json({ success: true, data: history });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async getLatestRates(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const baseCurrency = (req.query.base as string) || 'MXN';
+      const ratesMap = await currencyRatesService.getLatestRates(baseCurrency, req.tenantId);
+
+      // Convert Map to object for JSON response
+      const rates: Record<string, number> = {};
+      ratesMap.forEach((value, key) => {
+        rates[key] = value;
+      });
+
+      res.json({
+        success: true,
+        data: {
+          base: baseCurrency,
+          rates,
+          date: new Date().toISOString().split('T')[0],
+        }
+      });
+    } catch (error) {
+      next(error);
+    }
+  }
+
   // ========== UOM CATEGORIES ==========
   async getUomCategories(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
     try {
@@ -329,6 +635,56 @@ class CoreController {
     }
   }
 
+  async getUomByCode(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const uom = await uomService.findByCode(req.params.code);
+      if (!uom) {
+        res.status(404).json({ success: false, message: 'Unidad de medida no encontrada' });
+        return;
+      }
+      res.json({ success: true, data: uom });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async convertUom(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const { quantity, from_uom_id, fromUomId, to_uom_id, toUomId } = req.body;
+      const fromId = from_uom_id ?? fromUomId;
+      const toId = to_uom_id ?? toUomId;
+
+      if (!quantity || !fromId || !toId) {
+        throw new ValidationError('Se requiere quantity, from_uom_id y to_uom_id');
+      }
+
+      const result = await uomService.convertQuantity(quantity, fromId, toId);
+      const fromUom = await uomService.findById(fromId);
+      const toUom = await uomService.findById(toId);
+
+      res.json({
+        success: true,
+        data: {
+          originalQuantity: quantity,
+          originalUom: fromUom.name,
+          convertedQuantity: result,
+          targetUom: toUom.name,
+        }
+      });
+    } catch (error) {
+      next(error);
+    }
+  }
+
+  async getUomConversions(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
+    try {
+      const result = await uomService.getConversionTable(req.params.categoryId);
+      res.json({ success: true, data: result });
+    } catch (error) {
+      next(error);
+    }
+  }
+
   // ========== PRODUCT CATEGORIES ==========
   async getProductCategories(req: AuthenticatedRequest, res: Response, next: NextFunction): Promise<void> {
     try {
diff --git a/src/modules/core/core.routes.ts b/src/modules/core/core.routes.ts
index f27ab97..ef7d7f7 100644
--- a/src/modules/core/core.routes.ts
+++ b/src/modules/core/core.routes.ts
@@ -21,16 +21,50 @@ router.put('/currencies/:id', requireRoles('admin', 'super_admin'), (req, res, n
 router.get('/countries', (req, res, next) => coreController.getCountries(req, res, next));
 router.get('/countries/:id', (req, res, next) => coreController.getCountry(req, res, next));
 
+// ========== STATES ==========
+router.get('/states', (req, res, next) => coreController.getStates(req, res, next));
+router.get('/states/:id', (req, res, next) => coreController.getState(req, res, next));
+router.get('/countries/:countryId/states', (req, res, next) => coreController.getStatesByCountry(req, res, next));
+router.get('/countries/code/:countryCode/states', (req, res, next) => coreController.getStatesByCountryCode(req, res, next));
+router.post('/states', requireRoles('admin', 'super_admin'), (req, res, next) =>
+  coreController.createState(req, res, next)
+);
+router.put('/states/:id', requireRoles('admin', 'super_admin'), (req, res, next) =>
+  coreController.updateState(req, res, next)
+);
+router.delete('/states/:id', requireRoles('admin', 'super_admin'), (req, res, next) =>
+  coreController.deleteState(req, res, next)
+);
+
+// ========== CURRENCY RATES ==========
+router.get('/currency-rates', (req, res, next) => coreController.getCurrencyRates(req, res, next));
+router.get('/currency-rates/latest', (req, res, next) => coreController.getLatestRates(req, res, next));
+router.get('/currency-rates/rate/:from/:to', (req, res, next) => coreController.getLatestRate(req, res, next));
+router.get('/currency-rates/history/:from/:to', (req, res, next) => coreController.getCurrencyRateHistory(req, res, next));
+router.get('/currency-rates/:id', (req, res, next) => coreController.getCurrencyRate(req, res, next));
+router.post('/currency-rates', requireRoles('admin', 'manager', 'super_admin'), (req, res, next) =>
+  coreController.createCurrencyRate(req, res, next)
+);
+router.post('/currency-rates/convert', (req, res, next) => coreController.convertCurrency(req, res, next));
+router.delete('/currency-rates/:id', requireRoles('admin', 'super_admin'), (req, res, next) =>
+  coreController.deleteCurrencyRate(req, res, next)
+);
+
 // ========== UOM CATEGORIES ==========
 router.get('/uom-categories', (req, res, next) => coreController.getUomCategories(req, res, next));
 router.get('/uom-categories/:id', (req, res, next) => coreController.getUomCategory(req, res, next));
 
 // ========== UOM ==========
 router.get('/uom', (req, res, next) => coreController.getUoms(req, res, next));
+router.get('/uom/by-code/:code', (req, res, next) => coreController.getUomByCode(req, res, next));
 router.get('/uom/:id', (req, res, next) => coreController.getUom(req, res, next));
 router.post('/uom', requireRoles('admin', 'super_admin'), (req, res, next) =>
   coreController.createUom(req, res, next)
 );
+router.post('/uom/convert', (req, res, next) => coreController.convertUom(req, res, next));
+router.get('/uom-categories/:categoryId/conversions', (req, res, next) =>
+  coreController.getUomConversions(req, res, next)
+);
 router.put('/uom/:id', requireRoles('admin', 'super_admin'), (req, res, next) =>
   coreController.updateUom(req, res, next)
 );
diff --git a/src/modules/core/currency-rates.service.ts b/src/modules/core/currency-rates.service.ts
new file mode 100644
index 0000000..694b8c1
--- /dev/null
+++ b/src/modules/core/currency-rates.service.ts
@@ -0,0 +1,269 @@
+import { Repository, LessThanOrEqual } from 'typeorm';
+import { AppDataSource } from '../../config/typeorm.js';
+import { CurrencyRate, RateSource } from './entities/currency-rate.entity.js';
+import { Currency } from './entities/currency.entity.js';
+import { NotFoundError } from '../../shared/errors/index.js';
+import { logger } from '../../shared/utils/logger.js';
+
+export interface CreateCurrencyRateDto {
+  tenantId?: string;
+  fromCurrencyCode: string;
+  toCurrencyCode: string;
+  rate: number;
+  rateDate: Date;
+  source?: RateSource;
+  createdBy?: string;
+}
+
+export interface CurrencyRateFilter {
+  tenantId?: string;
+  fromCurrencyCode?: string;
+  toCurrencyCode?: string;
+  dateFrom?: Date;
+  dateTo?: Date;
+  limit?: number;
+}
+
+export interface ConvertCurrencyDto {
+  amount: number;
+  fromCurrencyCode: string;
+  toCurrencyCode: string;
+  date?: Date;
+  tenantId?: string;
+}
+
+class CurrencyRatesService {
+  private repository: Repository<CurrencyRate>;
+  private currencyRepository: Repository<Currency>;
+
+  constructor() {
+    this.repository = AppDataSource.getRepository(CurrencyRate);
+    this.currencyRepository = AppDataSource.getRepository(Currency);
+  }
+
+  async findAll(filter: CurrencyRateFilter = {}): Promise<CurrencyRate[]> {
+    logger.debug('Finding currency rates', { filter });
+
+    const query = this.repository
+      .createQueryBuilder('rate')
+      .leftJoinAndSelect('rate.fromCurrency', 'fromCurrency')
+      .leftJoinAndSelect('rate.toCurrency', 'toCurrency');
+
+    if (filter.tenantId) {
+      query.andWhere('(rate.tenantId = :tenantId OR rate.tenantId IS NULL)', {
+        tenantId: filter.tenantId,
+      });
+    }
+
+    if (filter.fromCurrencyCode) {
+      query.andWhere('fromCurrency.code = :fromCode', {
+        fromCode: filter.fromCurrencyCode.toUpperCase(),
+      });
+    }
+
+    if (filter.toCurrencyCode) {
+      query.andWhere('toCurrency.code = :toCode', {
+        toCode: filter.toCurrencyCode.toUpperCase(),
+      });
+    }
+
+    if (filter.dateFrom) {
+      query.andWhere('rate.rateDate >= :dateFrom', { dateFrom: filter.dateFrom });
+    }
+
+    if (filter.dateTo) {
+      query.andWhere('rate.rateDate <= :dateTo', { dateTo: filter.dateTo });
+    }
+
+    query.orderBy('rate.rateDate', 'DESC');
+
+    if (filter.limit) {
+      query.take(filter.limit);
+    }
+
+    return query.getMany();
+  }
+
+  async findById(id: string): Promise<CurrencyRate> {
+    logger.debug('Finding currency rate by id', { id });
+
+    const rate = await this.repository.findOne({
+      where: { id },
+      relations: ['fromCurrency', 'toCurrency'],
+    });
+
+    if (!rate) {
+      throw new NotFoundError('Tipo de cambio no encontrado');
+    }
+
+    return rate;
+  }
+
+  async getRate(
+    fromCurrencyCode: string,
+    toCurrencyCode: string,
+    date: Date = new Date(),
+    tenantId?: string
+  ): Promise<number | null> {
+    logger.debug('Getting currency rate', { fromCurrencyCode, toCurrencyCode, date, tenantId });
+
+    // Same currency = rate 1
+    if (fromCurrencyCode.toUpperCase() === toCurrencyCode.toUpperCase()) {
+      return 1;
+    }
+
+    // Find direct rate
+    const directRate = await this.repository
+      .createQueryBuilder('rate')
+      .leftJoin('rate.fromCurrency', 'fromCurrency')
+      .leftJoin('rate.toCurrency', 'toCurrency')
+      .where('fromCurrency.code = :fromCode', { fromCode: fromCurrencyCode.toUpperCase() })
+      .andWhere('toCurrency.code = :toCode', { toCode: toCurrencyCode.toUpperCase() })
+      .andWhere('rate.rateDate <= :date', { date })
+      .andWhere('(rate.tenantId = :tenantId OR rate.tenantId IS NULL)', { tenantId: tenantId || null })
+      .orderBy('rate.rateDate', 'DESC')
+      .addOrderBy('rate.tenantId', 'DESC', 'NULLS LAST')
+      .getOne();
+
+    if (directRate) {
+      return Number(directRate.rate);
+    }
+
+    // Try inverse rate
+    const inverseRate = await this.repository
+      .createQueryBuilder('rate')
+      .leftJoin('rate.fromCurrency', 'fromCurrency')
+      .leftJoin('rate.toCurrency', 'toCurrency')
+      .where('fromCurrency.code = :toCode', { toCode: toCurrencyCode.toUpperCase() })
+      .andWhere('toCurrency.code = :fromCode', { fromCode: fromCurrencyCode.toUpperCase() })
+      .andWhere('rate.rateDate <= :date', { date })
+      .andWhere('(rate.tenantId = :tenantId OR rate.tenantId IS NULL)', { tenantId: tenantId || null })
+      .orderBy('rate.rateDate', 'DESC')
+      .addOrderBy('rate.tenantId', 'DESC', 'NULLS LAST')
+      .getOne();
+
+    if (inverseRate) {
+      return 1 / Number(inverseRate.rate);
+    }
+
+    return null;
+  }
+
+  async convert(dto: ConvertCurrencyDto): Promise<{ amount: number; rate: number } | null> {
+    logger.debug('Converting currency', dto);
+
+    const rate = await this.getRate(
+      dto.fromCurrencyCode,
+      dto.toCurrencyCode,
+      dto.date || new Date(),
+      dto.tenantId
+    );
+
+    if (rate === null) {
+      return null;
+    }
+
+    return {
+      amount: dto.amount * rate,
+      rate,
+    };
+  }
+
+  async create(dto: CreateCurrencyRateDto): Promise<CurrencyRate> {
+    logger.info('Creating currency rate', { dto });
+
+    // Get currency IDs
+    const fromCurrency = await this.currencyRepository.findOne({
+      where: { code: dto.fromCurrencyCode.toUpperCase() },
+    });
+    if (!fromCurrency) {
+      throw new NotFoundError(`Moneda ${dto.fromCurrencyCode} no encontrada`);
+    }
+
+    const toCurrency = await this.currencyRepository.findOne({
+      where: { code: dto.toCurrencyCode.toUpperCase() },
+    });
+    if (!toCurrency) {
+      throw new NotFoundError(`Moneda ${dto.toCurrencyCode} no encontrada`);
+    }
+
+    // Check if rate already exists for this date
+    const existing = await this.repository.findOne({
+      where: {
+        tenantId: dto.tenantId || undefined,
+        fromCurrencyId: fromCurrency.id,
+        toCurrencyId: toCurrency.id,
+        rateDate: dto.rateDate,
+      },
+    });
+
+    if (existing) {
+      // Update existing rate
+      existing.rate = dto.rate;
+      existing.source = dto.source || 'manual';
+      return this.repository.save(existing);
+    }
+
+    const rate = this.repository.create({
+      tenantId: dto.tenantId || null,
+      fromCurrencyId: fromCurrency.id,
+      toCurrencyId: toCurrency.id,
+      rate: dto.rate,
+      rateDate: dto.rateDate,
+      source: dto.source || 'manual',
+      createdBy: dto.createdBy || null,
+    });
+
+    return this.repository.save(rate);
+  }
+
+  async delete(id: string): Promise<void> {
+    logger.info('Deleting currency rate', { id });
+
+    const rate = await this.findById(id);
+    await this.repository.remove(rate);
+  }
+
+  async getHistory(
+    fromCurrencyCode: string,
+    toCurrencyCode: string,
+    days: number = 30,
+    tenantId?: string
+  ): Promise<CurrencyRate[]> {
+    logger.debug('Getting rate history', { fromCurrencyCode, toCurrencyCode, days, tenantId });
+
+    const dateFrom = new Date();
+    dateFrom.setDate(dateFrom.getDate() - days);
+
+    return this.findAll({
+      fromCurrencyCode,
+      toCurrencyCode,
+      dateFrom,
+      tenantId,
+      limit: days,
+    });
+  }
+
+  async getLatestRates(baseCurrencyCode: string = 'MXN', tenantId?: string): Promise<Map<string, number>> {
+    logger.debug('Getting latest rates', { baseCurrencyCode, tenantId });
+
+    const rates = new Map<string, number>();
+    const currencies = await this.currencyRepository.find({ where: { active: true } });
+
+    for (const currency of currencies) {
+      if (currency.code === baseCurrencyCode.toUpperCase()) {
+        rates.set(currency.code, 1);
+        continue;
+      }
+
+      const rate = await this.getRate(baseCurrencyCode, currency.code, new Date(), tenantId);
+      if (rate !== null) {
+        rates.set(currency.code, rate);
+      }
+    }
+
+    return rates;
+  }
+}
+
+export const currencyRatesService = new CurrencyRatesService();
diff --git a/src/modules/core/entities/currency-rate.entity.ts b/src/modules/core/entities/currency-rate.entity.ts
new file mode 100644
index 0000000..1be963b
--- /dev/null
+++ b/src/modules/core/entities/currency-rate.entity.ts
@@ -0,0 +1,55 @@
+import {
+  Entity,
+  PrimaryGeneratedColumn,
+  Column,
+  CreateDateColumn,
+  Index,
+  ManyToOne,
+  JoinColumn,
+} from 'typeorm';
+import { Currency } from './currency.entity.js';
+
+export type RateSource = 'manual' | 'banxico' | 'xe' | 'openexchange';
+
+@Entity({ schema: 'core', name: 'currency_rates' })
+@Index('idx_currency_rates_tenant', ['tenantId'])
+@Index('idx_currency_rates_from', ['fromCurrencyId'])
+@Index('idx_currency_rates_to', ['toCurrencyId'])
+@Index('idx_currency_rates_date', ['rateDate'])
+@Index('idx_currency_rates_lookup', ['fromCurrencyId', 'toCurrencyId', 'rateDate'])
+export class CurrencyRate {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column({ type: 'uuid', name: 'tenant_id', nullable: true })
+  tenantId: string | null;
+
+  @Column({ type: 'uuid', name: 'from_currency_id', nullable: false })
+  fromCurrencyId: string;
+
+  @ManyToOne(() => Currency)
+  @JoinColumn({ name: 'from_currency_id' })
+  fromCurrency: Currency;
+
+  @Column({ type: 'uuid', name: 'to_currency_id', nullable: false })
+  toCurrencyId: string;
+
+  @ManyToOne(() => Currency)
+  @JoinColumn({ name: 'to_currency_id' })
+  toCurrency: Currency;
+
+  @Column({ type: 'decimal', precision: 18, scale: 8, nullable: false })
+  rate: number;
+
+  @Column({ type: 'date', name: 'rate_date', nullable: false })
+  rateDate: Date;
+
+  @Column({ type: 'varchar', length: 50, default: 'manual' })
+  source: RateSource;
+
+  @Column({ type: 'uuid', name: 'created_by', nullable: true })
+  createdBy: string | null;
+
+  @CreateDateColumn({ name: 'created_at', type: 'timestamptz' })
+  createdAt: Date;
+}
diff --git a/src/modules/core/entities/index.ts b/src/modules/core/entities/index.ts
index 7abd07e..db947b6 100644
--- a/src/modules/core/entities/index.ts
+++ b/src/modules/core/entities/index.ts
@@ -1,5 +1,7 @@
 export { Currency } from './currency.entity.js';
 export { Country } from './country.entity.js';
+export { State } from './state.entity.js';
+export { CurrencyRate, RateSource } from './currency-rate.entity.js';
 export { UomCategory } from './uom-category.entity.js';
 export { Uom, UomType } from './uom.entity.js';
 export { ProductCategory } from './product-category.entity.js';
diff --git a/src/modules/core/entities/state.entity.ts b/src/modules/core/entities/state.entity.ts
new file mode 100644
index 0000000..0355f5e
--- /dev/null
+++ b/src/modules/core/entities/state.entity.ts
@@ -0,0 +1,45 @@
+import {
+  Entity,
+  PrimaryGeneratedColumn,
+  Column,
+  CreateDateColumn,
+  UpdateDateColumn,
+  Index,
+  ManyToOne,
+  JoinColumn,
+} from 'typeorm';
+import { Country } from './country.entity.js';
+
+@Entity({ schema: 'core', name: 'states' })
+@Index('idx_states_country', ['countryId'])
+@Index('idx_states_code', ['code'])
+@Index('idx_states_country_code', ['countryId', 'code'], { unique: true })
+export class State {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column({ type: 'uuid', name: 'country_id', nullable: false })
+  countryId: string;
+
+  @ManyToOne(() => Country, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'country_id' })
+  country: Country;
+
+  @Column({ type: 'varchar', length: 10, nullable: false })
+  code: string;
+
+  @Column({ type: 'varchar', length: 255, nullable: false })
+  name: string;
+
+  @Column({ type: 'varchar', length: 50, nullable: true })
+  timezone: string | null;
+
+  @Column({ type: 'boolean', name: 'is_active', default: true })
+  isActive: boolean;
+
+  @CreateDateColumn({ name: 'created_at', type: 'timestamptz' })
+  createdAt: Date;
+
+  @UpdateDateColumn({ name: 'updated_at', type: 'timestamptz' })
+  updatedAt: Date;
+}
diff --git a/src/modules/core/states.service.ts b/src/modules/core/states.service.ts
new file mode 100644
index 0000000..c89a9a9
--- /dev/null
+++ b/src/modules/core/states.service.ts
@@ -0,0 +1,148 @@
+import { Repository } from 'typeorm';
+import { AppDataSource } from '../../config/typeorm.js';
+import { State } from './entities/state.entity.js';
+import { NotFoundError } from '../../shared/errors/index.js';
+import { logger } from '../../shared/utils/logger.js';
+
+export interface CreateStateDto {
+  countryId: string;
+  code: string;
+  name: string;
+  timezone?: string;
+  isActive?: boolean;
+}
+
+export interface UpdateStateDto {
+  name?: string;
+  timezone?: string;
+  isActive?: boolean;
+}
+
+export interface StateFilter {
+  countryId?: string;
+  countryCode?: string;
+  isActive?: boolean;
+}
+
+class StatesService {
+  private repository: Repository<State>;
+
+  constructor() {
+    this.repository = AppDataSource.getRepository(State);
+  }
+
+  async findAll(filter: StateFilter = {}): Promise<State[]> {
+    logger.debug('Finding all states', { filter });
+
+    const query = this.repository
+      .createQueryBuilder('state')
+      .leftJoinAndSelect('state.country', 'country');
+
+    if (filter.countryId) {
+      query.andWhere('state.countryId = :countryId', { countryId: filter.countryId });
+    }
+
+    if (filter.countryCode) {
+      query.andWhere('country.code = :countryCode', { countryCode: filter.countryCode.toUpperCase() });
+    }
+
+    if (filter.isActive !== undefined) {
+      query.andWhere('state.isActive = :isActive', { isActive: filter.isActive });
+    }
+
+    query.orderBy('state.name', 'ASC');
+
+    return query.getMany();
+  }
+
+  async findById(id: string): Promise<State> {
+    logger.debug('Finding state by id', { id });
+
+    const state = await this.repository.findOne({
+      where: { id },
+      relations: ['country'],
+    });
+
+    if (!state) {
+      throw new NotFoundError('Estado no encontrado');
+    }
+
+    return state;
+  }
+
+  async findByCode(countryId: string, code: string): Promise<State | null> {
+    logger.debug('Finding state by code', { countryId, code });
+
+    return this.repository.findOne({
+      where: { countryId, code: code.toUpperCase() },
+      relations: ['country'],
+    });
+  }
+
+  async findByCountry(countryId: string): Promise<State[]> {
+    logger.debug('Finding states by country', { countryId });
+
+    return this.repository.find({
+      where: { countryId, isActive: true },
+      relations: ['country'],
+      order: { name: 'ASC' },
+    });
+  }
+
+  async findByCountryCode(countryCode: string): Promise<State[]> {
+    logger.debug('Finding states by country code', { countryCode });
+
+    return this.repository
+      .createQueryBuilder('state')
+      .leftJoinAndSelect('state.country', 'country')
+      .where('country.code = :countryCode', { countryCode: countryCode.toUpperCase() })
+      .andWhere('state.isActive = :isActive', { isActive: true })
+      .orderBy('state.name', 'ASC')
+      .getMany();
+  }
+
+  async create(dto: CreateStateDto): Promise<State> {
+    logger.info('Creating state', { dto });
+
+    // Check if state already exists for this country
+    const existing = await this.findByCode(dto.countryId, dto.code);
+    if (existing) {
+      throw new Error(`Estado con código ${dto.code} ya existe para este país`);
+    }
+
+    const state = this.repository.create({
+      ...dto,
+      code: dto.code.toUpperCase(),
+      isActive: dto.isActive ?? true,
+    });
+
+    return this.repository.save(state);
+  }
+
+  async update(id: string, dto: UpdateStateDto): Promise<State> {
+    logger.info('Updating state', { id, dto });
+
+    const state = await this.findById(id);
+    Object.assign(state, dto);
+
+    return this.repository.save(state);
+  }
+
+  async delete(id: string): Promise<void> {
+    logger.info('Deleting state', { id });
+
+    const state = await this.findById(id);
+    await this.repository.remove(state);
+  }
+
+  async setActive(id: string, isActive: boolean): Promise<State> {
+    logger.info('Setting state active status', { id, isActive });
+
+    const state = await this.findById(id);
+    state.isActive = isActive;
+
+    return this.repository.save(state);
+  }
+}
+
+export const statesService = new StatesService();
diff --git a/src/modules/core/uom.service.ts b/src/modules/core/uom.service.ts
index dc3abd6..93c0ace 100644
--- a/src/modules/core/uom.service.ts
+++ b/src/modules/core/uom.service.ts
@@ -157,6 +157,93 @@ class UomService {
 
     return updated;
   }
+
+  /**
+   * Convert quantity from one UoM to another
+   * Both UoMs must be in the same category
+   */
+  async convertQuantity(quantity: number, fromUomId: string, toUomId: string): Promise<number> {
+    logger.debug('Converting quantity', { quantity, fromUomId, toUomId });
+
+    // Same UoM = no conversion needed
+    if (fromUomId === toUomId) {
+      return quantity;
+    }
+
+    const fromUom = await this.findById(fromUomId);
+    const toUom = await this.findById(toUomId);
+
+    // Validate same category
+    if (fromUom.categoryId !== toUom.categoryId) {
+      throw new Error('No se pueden convertir unidades de diferentes categorías');
+    }
+
+    // Convert: first to reference unit, then to target unit
+    // quantity * fromFactor = reference quantity
+    // reference quantity / toFactor = target quantity
+    const result = (quantity * fromUom.factor) / toUom.factor;
+
+    logger.debug('Conversion result', {
+      quantity,
+      fromUom: fromUom.name,
+      toUom: toUom.name,
+      result
+    });
+
+    return result;
+  }
+
+  /**
+   * Get the reference UoM for a category
+   */
+  async getReferenceUom(categoryId: string): Promise<Uom | null> {
+    logger.debug('Getting reference UoM', { categoryId });
+
+    return this.repository.findOne({
+      where: {
+        categoryId,
+        uomType: 'reference' as UomType,
+        active: true,
+      },
+      relations: ['category'],
+    });
+  }
+
+  /**
+   * Find UoM by code
+   */
+  async findByCode(code: string): Promise<Uom | null> {
+    logger.debug('Finding UoM by code', { code });
+
+    return this.repository.findOne({
+      where: { code },
+      relations: ['category'],
+    });
+  }
+
+  /**
+   * Get all UoMs in a category with their conversion factors
+   */
+  async getConversionTable(categoryId: string): Promise<{
+    referenceUom: Uom;
+    conversions: Array<{ uom: Uom; toReference: number; fromReference: number }>;
+  }> {
+    logger.debug('Getting conversion table', { categoryId });
+
+    const referenceUom = await this.getReferenceUom(categoryId);
+    if (!referenceUom) {
+      throw new NotFoundError('No se encontró unidad de referencia para esta categoría');
+    }
+
+    const uoms = await this.findAll(categoryId, true);
+    const conversions = uoms.map(uom => ({
+      uom,
+      toReference: uom.factor,        // Multiply by this to get reference unit
+      fromReference: 1 / uom.factor,  // Multiply by this to get this unit from reference
+    }));
+
+    return { referenceUom, conversions };
+  }
 }
 
 export const uomService = new UomService();