How to Build a Complete Billing & Inventory System in Google Sheets - E47

Sixteen modules and fifteen sheets doing the whole back office of a trading business: billing, stock, purchasing, receivables, returns, expenses and the ledger that ties them together — all on Google Sheets, with two roles deciding who reaches what.

Billing that knows the difference between a quote and a sale

The same screen issues an invoice, a proforma or a quotation — and stock is deducted only on a real invoice, so quoting a customer never touches your inventory. Lines carry their own unit price override and discount, with an overall discount, shipping and notes on top. Payment terms run net 30 or net 60, invoices generate as a printable bill, email to the customer, or duplicate into the next one. The pipeline tabs across the top cut the list to pending, partial, paid or cancelled, and an overdue reminder can email every late customer in one action.

Stock with the details that matter

Products carry SKU, brand, HSN code, tax rate, purchase price, sale price, minimum sale price, default discount, rack location, weight and expiry, with an image in Drive. Each has a reorder level, and anything below it raises a badge on the sidebar so the count is visible before you go looking. Add or deduct stock from the row itself, or print the product list to hand a field salesman for order taking.

Buying, returning and getting paid

Purchase orders are raised by a user, approved by the admin, and marked received — which is what updates the stock. Returns load their invoice's items, take the returned quantity and restore it to stock. Payments record both ways, in from customers and out to suppliers, with a guard that refuses more than the balance due and an email confirming the receipt. Each customer keeps a ledger with balance, unpaid bills, return history and a printable account statement.

Reporting and the automatic emails

Sales, profit and loss, and customer-wise reports run over any date range, with a full ledger exportable to PDF. Five automations run without you: welcome email on a new user, return confirmation, forgot-password OTP, a daily low-stock alert and a daily sales summary to the admins. Settings hold your currency, app name and logo; activity logs hold everything else.