The new Sri Lanka tax invoice format (2026)

If you are VAT registered in Sri Lanka, the invoice you send has to follow a specific format. From 1 April 2026, an updated tax invoice format applies, and getting a field wrong is no longer a small detail. A buyer needs a valid tax invoice to claim their input VAT, so an incomplete invoice can hold up their payment and your cash flow.

This is a plain guide to what a compliant Sri Lankan tax invoice needs to contain. It is general information, not tax advice, so confirm the current rules with the Inland Revenue Department (IRD) or your accountant before you finalise your template.

What changed in 2026

The Inland Revenue Department published updated technical specifications for tax invoices, and the new format applies to invoices issued on or after 1 April 2026. The goal is cleaner, more consistent invoices that support VAT administration and, later, the move toward national e-invoicing.

For most small businesses the practical effect is simple: your invoice template needs to carry a fixed set of fields, laid out clearly, every time.

What a compliant tax invoice must show

A Sri Lankan tax invoice should carry all of the following.

• The words TAX INVOICE in a clear, visible position
• Your business name, address, and 9-digit TIN (Taxpayer Identification Number)
• Your VAT registration number
• The customer's name and address, and their TIN where required
• A unique invoice number and the invoice date
• The date of supply, if it differs from the invoice date
• A description of the goods or services supplied
• The quantity and unit price for each line
• The value before VAT, the VAT at 18%, and the total payable in LKR

The two mistakes we see most often are a missing or non-unique invoice number and a missing TIN. Both are avoidable, and both matter to the customer who wants to claim input VAT.

Why the invoice number matters more than it looks

A tax invoice number has to be unique and, ideally, sequential. When numbering is done by hand in a spreadsheet or a document template, it is easy to repeat a number or skip one during a busy week. Once customers and the IRD start asking for clean references, gaps and duplicates become a real problem.

The safest approach is a system that assigns the next number automatically, so every invoice is unique without anyone having to remember the last one used.

A quick pre-send checklist

Before an invoice goes out, run through this:

• Does it say TAX INVOICE at the top?
• Is your TIN and VAT number on it?
• Is the invoice number unique and in sequence?
• Is VAT shown as a separate line at 18%?
• Is the total in LKR correct and clearly stated?

If you can answer yes to all five, your invoice is in good shape.

Where Myn fits

Keeping up with a fixed format is exactly the kind of thing software should handle for you. Myn issues invoices with your business details, automatic sequential numbering, VAT, and totals in LKR already in place, so a compliant tax invoice is the default rather than something you rebuild each time. You can read more about how Myn is built for Sri Lankan SMEs on our [home page](/) or in our FAQ. If you are weighing your options, our guide to the best invoicing software for Sri Lankan SMEs compares the main choices.

Rules and thresholds are changing through 2026 and 2027, so treat this as a starting point and check the latest guidance from the IRD before relying on it. For the wider set of 2026 changes, see our guide on the new Rs 36 million VAT registration threshold.