diff --git a/middleware/expenseValidator.js b/middleware/expenseValidator.js
new file mode 100644
index 00000000..30501768
--- /dev/null
+++ b/middleware/expenseValidator.js
@@ -0,0 +1,31 @@
+const Joi = require('joi');
+const currencyService = require('../services/currencyService');
+
+const expenseSchema = Joi.object({
+  description: Joi.string().trim().max(100).required(),
+  amount: Joi.number().min(0.01).required(),
+  currency: Joi.string().uppercase().optional(),
+  category: Joi.string().valid('food', 'transport', 'entertainment', 'utilities', 'healthcare', 'shopping', 'other').required(),
+  type: Joi.string().valid('income', 'expense').required(),
+  merchant: Joi.string().trim().max(50).optional(),
+  date: Joi.date().optional(),
+  workspaceId: Joi.string().hex().length(24).optional()
+});
+
+const expenseValidator = async (req, res, next) => {
+  const { error, value } = expenseSchema.validate(req.body);
+  if (error) return res.status(400).json({ error: error.details[0].message });
+
+  const user = req.user; // Assuming auth middleware sets req.user
+  const expenseCurrency = value.currency || user.preferredCurrency;
+
+  if (!currencyService.isValidCurrency(expenseCurrency)) {
+    return res.status(400).json({ error: 'Invalid currency code' });
+  }
+
+  req.validatedExpense = value;
+  req.expenseCurrency = expenseCurrency;
+  next();
+};
+
+module.exports = expenseValidator;
diff --git a/routes/expenseCreation.js b/routes/expenseCreation.js
new file mode 100644
index 00000000..f2120b7f
--- /dev/null
+++ b/routes/expenseCreation.js
@@ -0,0 +1,64 @@
+const express = require('express');
+const Expense = require('../models/Expense');
+const User = require('../models/User');
+const expenseValidator = require('../middleware/expenseValidator');
+const auth = require('../middleware/auth');
+const expenseService = require('../services/expenseService');
+const { convertExpenseAmount } = require('../utils/currencyUtils');
+
+const router = express.Router();
+
+// POST new expense for authenticated user
+router.post('/', auth, expenseValidator, async (req, res) => {
+  try {
+    const user = await User.findById(req.user._id);
+    const { validatedExpense: value, expenseCurrency } = req;
+
+    // Handle auto-categorization
+    const { finalCategory, autoCategorized } = await expenseService.handleAutoCategorization(value, req.user._id);
+
+    // Store original amount and currency
+    const expenseData = {
+      ...value,
+      category: finalCategory,
+      user: value.workspaceId ? req.user._id : req.user._id,
+      addedBy: req.user._id,
+      workspace: value.workspaceId || null,
+      originalAmount: value.amount,
+      originalCurrency: expenseCurrency,
+      amount: value.amount,
+      autoCategorized
+    };
+
+    // Handle currency conversion if needed
+    const conversionData = await expenseService.handleCurrencyConversion(value.amount, expenseCurrency, user.preferredCurrency);
+    Object.assign(expenseData, conversionData);
+
+    const expense = new Expense(expenseData);
+    await expense.save();
+
+    // Handle approval submission
+    const { requiresApproval, workflow } = await expenseService.handleApprovalSubmission(expense, req.user._id);
+
+    // Handle budget update
+    const amountForBudget = expenseData.convertedAmount || value.amount;
+    await expenseService.handleBudgetUpdate(req.user._id, value.type, amountForBudget, value.category);
+
+    // Emit real-time update
+    const io = req.app.get('io');
+    const expenseForSocket = expenseService.prepareExpenseResponse(expense, user.preferredCurrency);
+    expenseService.emitRealTimeUpdate(io, req.user._id, 'expense_created', expenseForSocket);
+
+    const response = {
+      ...expenseService.prepareExpenseResponse(expense, user.preferredCurrency),
+      requiresApproval,
+      workflow: workflow ? { _id: workflow._id, status: workflow.status } : null
+    };
+
+    res.status(201).json(response);
+  } catch (error) {
+    res.status(500).json({ error: error.message });
+  }
+});
+
+module.exports = router;
diff --git a/routes/expenseExport.js b/routes/expenseExport.js
new file mode 100644
index 00000000..833dc831
--- /dev/null
+++ b/routes/expenseExport.js
@@ -0,0 +1,43 @@
+const express = require('express');
+const exportService = require('../services/exportService');
+const auth = require('../middleware/auth');
+
+const router = express.Router();
+
+// GET export expenses to CSV
+router.get('/export', auth, async (req, res) => {
+  try {
+    const { format, startDate, endDate, category } = req.query;
+
+    // Validate format
+    if (format && format !== 'csv') {
+      return res.status(400).json({ error: 'Only CSV format is supported' });
+    }
+
+    // Get expenses using export service
+    const expenses = await exportService.getExpensesForExport(req.user._id, {
+      startDate,
+      endDate,
+      category,
+      type: 'all' // Include both income and expenses
+    });
+
+    if (expenses.length === 0) {
+      return res.status(404).json({ error: 'No expenses found for the selected filters' });
+    }
+
+    // Generate CSV using ExportService
+    const csv = exportService.generateCSV(expenses);
+
+    // Set CSV headers
+    res.setHeader('Content-Type', 'text/csv');
+    res.setHeader('Content-Disposition', 'attachment; filename="expenses.csv"');
+
+    res.send(csv);
+  } catch (error) {
+    console.error('Export error:', error);
+    res.status(500).json({ error: 'Failed to export expenses' });
+  }
+});
+
+module.exports = router;
diff --git a/routes/expenseUpdate.js b/routes/expenseUpdate.js
new file mode 100644
index 00000000..5671efd3
--- /dev/null
+++ b/routes/expenseUpdate.js
@@ -0,0 +1,51 @@
+const express = require('express');
+const Expense = require('../models/Expense');
+const User = require('../models/User');
+const expenseValidator = require('../middleware/expenseValidator');
+const auth = require('../middleware/auth');
+const expenseService = require('../services/expenseService');
+
+const router = express.Router();
+
+// PUT update expense for authenticated user
+router.put('/:id', auth, expenseValidator, async (req, res) => {
+  try {
+    const user = await User.findById(req.user._id);
+    const { validatedExpense: value, expenseCurrency } = req;
+
+    // Prepare update data
+    const updateData = {
+      ...value,
+      originalAmount: value.amount,
+      originalCurrency: expenseCurrency,
+      amount: value.amount
+    };
+
+    // Handle currency conversion if needed
+    const conversionData = await expenseService.handleCurrencyConversion(value.amount, expenseCurrency, user.preferredCurrency);
+    Object.assign(updateData, conversionData);
+
+    const expense = await Expense.findOneAndUpdate(
+      { _id: req.params.id, user: req.user._id },
+      updateData,
+      { new: true }
+    );
+    if (!expense) return res.status(404).json({ error: 'Expense not found' });
+
+    // Handle budget update
+    await expenseService.handleBudgetUpdate(req.user._id, value.type, updateData.convertedAmount || value.amount, value.category);
+
+    // Emit real-time update
+    const io = req.app.get('io');
+    const expenseForSocket = expenseService.prepareExpenseResponse(expense, user.preferredCurrency);
+    expenseService.emitRealTimeUpdate(io, req.user._id, 'expense_updated', expenseForSocket);
+
+    const response = expenseService.prepareExpenseResponse(expense, user.preferredCurrency);
+
+    res.json(response);
+  } catch (error) {
+    res.status(500).json({ error: error.message });
+  }
+});
+
+module.exports = router;
diff --git a/server.js b/server.js
index e23e30f2..60dc9224 100644
--- a/server.js
+++ b/server.js
@@ -28,6 +28,9 @@ require('dotenv').config();
 
 const authRoutes = require('./routes/auth');
 const expenseRoutes = require('./routes/expenses');
+const expenseCreationRoutes = require('./routes/expenseCreation');
+const expenseUpdateRoutes = require('./routes/expenseUpdate');
+const expenseExportRoutes = require('./routes/expenseExport');
 const syncRoutes = require('./routes/sync');
 const splitsRoutes = require('./routes/splits');
 const groupsRoutes = require('./routes/groups');
diff --git a/utils/currencyUtils.js b/utils/currencyUtils.js
new file mode 100644
index 00000000..9c0caca4
--- /dev/null
+++ b/utils/currencyUtils.js
@@ -0,0 +1,32 @@
+const currencyService = require('../services/currencyService');
+
+const convertExpenseAmount = async (amount, fromCurrency, toCurrency) => {
+  if (fromCurrency === toCurrency) {
+    return { convertedAmount: amount, exchangeRate: 1 };
+  }
+  try {
+    const conversion = await currencyService.convertCurrency(amount, fromCurrency, toCurrency);
+    return { convertedAmount: conversion.convertedAmount, exchangeRate: conversion.exchangeRate };
+  } catch (error) {
+    console.error('Currency conversion failed:', error.message);
+    return null; // Or throw error, but for now return null to handle gracefully
+  }
+};
+
+const prepareExpenseWithDisplayAmounts = (expense, userPreferredCurrency) => {
+  const expenseObj = expense.toObject ? expense.toObject() : expense;
+  if (expenseObj.originalCurrency !== userPreferredCurrency) {
+    // Assuming convertedAmount is already set if conversion happened
+    expenseObj.displayAmount = expenseObj.convertedAmount || expenseObj.amount;
+    expenseObj.displayCurrency = userPreferredCurrency;
+  } else {
+    expenseObj.displayAmount = expenseObj.amount;
+    expenseObj.displayCurrency = expenseObj.originalCurrency;
+  }
+  return expenseObj;
+};
+
+module.exports = {
+  convertExpenseAmount,
+  prepareExpenseWithDisplayAmounts
+};