diff --git a/src/payments/billing.js b/src/payments/billing.js
new file mode 100644
index 000000000..06a139f08
--- /dev/null
+++ b/src/payments/billing.js
@@ -0,0 +1,53 @@
+// payments/billing.js
+const moment = require('moment');
+
+class Invoice {
+    constructor(userId, amount, dueDate) {
+        this.userId = userId;
+        this.amount = amount;
+        this.dueDate = dueDate;
+        this.isPaid = false;
+    }
+
+    markAsPaid() {
+        this.isPaid = true;
+        console.log(`Invoice for user ${this.userId} has been marked as paid.`);
+    }
+
+    getDetails() {
+        return {
+            userId: this.userId,
+            amount: this.amount,
+            dueDate: this.dueDate,
+            isPaid: this.isPaid,
+        };
+    }
+}
+
+class Billing {
+    constructor() {
+        this.invoices = [];
+    }
+
+    generateInvoice(userId, amount) {
+        const dueDate = moment().add(30, 'days').toDate(); // 30 days from now
+        const invoice = new Invoice(userId, amount, dueDate);
+        this.invoices.push(invoice);
+        console.log(`Invoice generated for user ${userId}: $${amount}, due on ${dueDate}`);
+        return invoice;
+    }
+
+    getInvoice(userId) {
+        return this.invoices.filter(invoice => invoice.userId === userId);
+    }
+
+    processPayment(userId, amount) {
+        const invoice = this.invoices.find(inv => inv.userId === userId && inv.amount === amount && !inv.isPaid);
+        if (!invoice) {
+            throw new Error('No unpaid invoice found for this user and amount.');
+        }
+        invoice.markAsPaid();
+    }
+}
+
+module.exports = Billing;