How to write an invoice in Sri Lanka

Writing an invoice sounds simple until you send your first one and the customer asks for a reference number, a breakdown, or a VAT amount you did not include. A clear invoice gets paid faster and makes you look like a business worth paying. Here is how to write one properly in Sri Lanka.

Start with the basics every invoice needs

Whether or not you are VAT registered, a good invoice should carry:

• Your business name, address, and contact details
• The customer's name and address
• A unique invoice number
• The invoice date
• A clear description of what you sold, with quantity and unit price
• The total amount due in LKR
• Your payment details and due date

The invoice number is the field people most often get wrong. Keep it unique and in sequence. If two invoices share a number, your records and your customer's records stop agreeing, and that costs you time later.

If you are VAT registered, it becomes a tax invoice

If your business is registered for VAT, you are not writing a plain invoice, you are writing a tax invoice, and it has extra requirements. On top of the basics above, include:

• The words TAX INVOICE clearly at the top
• Your 9-digit TIN and your VAT registration number
• The customer's TIN where required
• The value before VAT, the VAT at 18% shown separately, and the total payable

We cover this in detail in our guide to the Sri Lanka tax invoice format. If you are not sure whether you need to register, the Rs 36 million VAT threshold guide will help.

Write it in a clear order

A clean invoice reads top to bottom without the customer hunting for anything:

• Your details at the top, then the customer's details
• Invoice number and date next to each other
• The line items in a simple list, each with quantity, unit price, and line total
• Subtotal, then VAT if it applies, then the grand total
• Payment instructions and due date at the bottom

Clarity is not decoration. The easier it is to read, the faster it tends to get paid.

Set a due date and payment terms

An invoice without a due date is an invitation to be paid late. State exactly when payment is due, for example within 14 or 30 days, and how you would like to be paid. If you want to be firm about it, note any late-payment terms upfront rather than after the fact.

Once the invoice is sent, the job is not finished. Keeping track of which invoices are paid, due soon, or overdue is what actually protects your cash flow. We wrote about a cleaner way to follow up on unpaid invoices if you want a simple rhythm for that.

Stop rebuilding invoices from scratch

Most small businesses start in Excel or a Word template, and it works until it does not. Numbers get duplicated, customer details live in three places, and every new invoice takes longer than it should. We wrote about the signs it is time to move on in when a small business outgrows Excel.

Myn keeps your business details, customers, items, numbering, VAT, and payment status in one place, so writing the next invoice is a couple of clicks rather than a rebuild. Have a look at how it works on our [home page](/), or compare the alternatives in our guide to the best invoicing software for Sri Lankan SMEs.

This is general guidance. If your invoice needs to meet VAT rules, confirm the current requirements with the Inland Revenue Department or your accountant.