Invoice format for Sri Lankan small businesses (with free generator)

The first "real" invoice most small businesses send is copied from an old one someone emailed them in 2015. It usually works — until a company client's accounts department bounces it for a missing detail, and payment waits another month. Here is what an invoice needs, and the fastest way to produce one.

What every invoice must contain

• The word "Invoice" and a unique invoice number (INV-0001, INV-0002 — sequential, never reused).
• Your details: business name, address, phone — and business registration number if you have one; VAT/TIN if registered.
• The customer's name and address — company clients need this exactly right for their records.
• Date of issue and, if you give credit, the due date ("Net 30" means little here; write the actual date).
• Itemised lines: description, quantity, unit price, line total — then subtotal, any discount or tax, and the grand total in LKR.
• How to pay: bank, branch, account name and number. Missing payment details are the number-one self-inflicted payment delay.

Common mistakes that delay payment

• Reusing invoice numbers, which makes reconciliation impossible and audits unpleasant.
• Vague line items ("work done — Rs. 45,000") that invite queries instead of payment.
• No due date, which the customer reads as "whenever".
• Sending a photo of a handwritten bill to a corporate client.

The fast way: generate it

Duqit's free invoice generator produces a clean, correctly-structured invoice in your browser — fill in the details, print or save as PDF. Free, no sign-up, nothing stored.

When you outgrow one-off invoices

The generator is perfect for occasional billing. When invoicing becomes daily, you want numbering that increments itself, customer details that fill themselves in, unpaid invoices flagged in a list, and a bill the customer opens from a WhatsApp link. That is Duqit Business POS — invoicing, inventory and customer records for LKR 849/month after 3 free months.