How do I write a proper invoice in Pakistan?

Quick answer

A proper invoice shows your business name, address, and NTN (plus your sales-tax registration number and tax breakdown if you're registered), a unique invoice number and date, the customer's details, a clear description of goods/services with quantities and prices, the subtotal, any sales tax, and the total, along with payment terms and your bank details. Keeping correct invoices is essential for bookkeeping, tax input claims, and B2B credibility.