New VAT Invoice Format in Sri Lanka (October 2026): How to Update Your Billing, POS and ERP Software

Last updated 19 October 2026. This guide explains the software side of the change. Confirm how the rules apply to your business with your accountant or tax adviser.

Since 1 October 2026, every VAT-registered business in Sri Lanka must issue tax invoices in the new format set by the Inland Revenue Department (IRD). The new VAT invoice format in Sri Lanka isn’t just a new template. It needs a fixed invoice numbering structure, extra details about your customer and each item, and values shown in a specific way, which means most billing, POS and ERP systems have to be changed.

This guide covers what the new format requires, how the new invoice number works with examples, what to change in your software, and how to test it before an error costs your customers their input VAT claims.

What changed with the VAT invoice format, and when

The IRD first prescribed a standard tax invoice format in Gazette No. 2463/05 in November 2025, to apply from 1 January 2026. The start date was postponed several times, and a revised format was issued in Gazette Extraordinary No. 2481/22 on 27 March 2026. The IRD explained it in Circular SEC/2026/E/03 on 20 May 2026.

Gazette Extraordinary No. 2500/106, issued on 6 August 2026, moved the mandatory date for the revised format to 1 October 2026, citing the complexity of system changes for businesses. Only the date changed; the format and specifications in the March gazette still apply.

The IRD says non-compliant invoices may be rejected for input VAT credit, may cause inconsistencies in VAT returns and may draw extra audit attention, as well as penalties under the VAT Act. That makes this a customer issue as much as a tax issue: if your invoice is wrong, your VAT-registered customers may not be able to claim the VAT on it.

What every tax invoice must show

Field	What the format requires
Title	The words “TAX INVOICE”, displayed prominently
Supplier details	Your 9-digit TIN, registered business name and registered address, exactly as on your VAT registration certificate
Purchaser details	The customer’s TIN, name and address where the customer is VAT-registered, matching their VAT certificate
Invoice number	A unique serial number in the prescribed format (see the next section)
Invoice date	The date the invoice is issued
Date of supply	When the goods or services were supplied, which can differ from the invoice date
Description	A specific description of each item. Vague words such as “items”, “products”, “services” or “miscellaneous” are not acceptable
Quantity	In measurable units, such as pieces, kilograms, litres, hours, days or boxes
Values	Value excluding VAT, VAT amount and total including VAT, in LKR to two decimal places

You can keep your own layout, logo and branding and add extra columns, as long as every mandatory element is clearly identifiable. Tax invoices should cover only VAT-taxable supplies; exempt or out-of-scope items shouldn’t be included unless they’re an integral part of the taxable supply, and then they should be shown separately.

Foreign currency invoices: where the Central Bank has approved invoicing in foreign currency, the invoice must also show the value excluding VAT, the VAT amount and the total in LKR, converted at the rate the IRD specifies. Check the exact conversion rule with your adviser before you build it.

The new invoice number format, with examples

This is the change that affects software most. Every invoice number must follow this structure:

YYMMM_QQQQ_XXXXX

Part	Meaning	Rules
YY	Year of issue	Last two digits, for example 26 for 2026
MMM	Month of issue	First three letters in capitals, for example OCT
QQQQ	Your classification code	1 to 15 letters and/or numbers. Use it for branches, departments, projects, customers or invoice types
XXXXX	Running number	Digits only, no letters or symbols, continuing from your last invoice

The whole number must have no spaces and be no longer than 40 characters. The running number should continue in sequence; the IRD allows restarting it at the start of a new month or year only where the reason is beyond your control.

Examples

• 26OCT_COL_00125: a Colombo branch invoice issued in October 2026.
• 26OCT_KDY_00048: a Kandy branch invoice in the same month, with its own running number.
• 26NOV_ONLINE_01093: an online store invoice issued in November 2026.
• 26DEC_PRJ2041_00007: an invoice for a specific project.

Decide your classification codes once, document them and use them consistently. The same structure can also be used for proforma invoices and quotations, using the classification code to tell them apart.

Updating your billing, POS and ERP software for the new VAT invoice format

How much work this takes depends on what you use.

If you use off-the-shelf accounting or POS software

• Ask your vendor whether their current version supports the Gazette 2481/22 format, and in which release.
• Update to that version and check your invoice template against the field table above.
• Set up your classification codes and check the numbering settings produce the right structure.
• If your vendor doesn’t support it yet, ask for a date in writing. You may need a workaround or a different system.

If you use custom-built, older or heavily modified software

• Numbering: change the invoice number generator to build the YYMMM_QQQQ_ prefix from the issue date and your classification code, keep a separate running counter per sequence, and block numbers over 40 characters or with spaces.
• Concurrency: if several tills, branches or users issue invoices at once, make sure two invoices can never get the same number or leave unexplained gaps.
• Customer records: add a validated 9-digit TIN field and a VAT-registered flag to your customer master data, and stop VAT invoices for registered customers being issued without them.
• Dates: store the date of supply separately from the invoice date.
• Product data: replace generic item names with specific descriptions, and give every product or service a measurable unit.
• Calculations: show the value excluding VAT, the VAT amount and the total in LKR to two decimal places, and handle LKR conversion for approved foreign currency invoices.
• Templates: update printed, PDF and emailed invoices, including thermal receipts on POS printers, which often cut off long fields.
• Integrations: check that the new invoice numbers flow correctly into your accounting system, online store, CRM and VAT return schedules.

Credit notes, debit notes and sales to customers who aren’t VAT-registered aren’t covered in detail by the circular, so confirm their treatment with your tax adviser before you change them.

A testing checklist before you rely on it

1. Issue test invoices from every branch, till and channel, and check every mandatory field is present.
2. Check invoice numbers for the right year and month, no spaces and no more than 40 characters.
3. Test the change of month: the first invoice on the 1st should carry the new month code.
4. Issue invoices from several devices at the same moment and check for duplicate numbers.
5. Issue an invoice to a VAT-registered customer without a TIN and confirm the system stops it.
6. Print on every printer and paper size you use, including POS receipts, and check nothing is cut off.
7. Check the VAT, totals and rounding against a manual calculation.
8. Ask your accountant to review a sample of real invoices before and after go-live.

Common mistakes to avoid

• Using generic descriptions like “Services rendered” or “Goods” on invoices.
• Leaving the customer’s TIN off invoices to VAT-registered businesses.
• Resetting the running number every month without a reason outside your control.
• Letting different branches share one counter and clash, or invent their own number formats.
• Adding spaces or extra separators to the invoice number.
• Updating the PDF invoice but forgetting POS receipts, emailed invoices or the online store.

Next step: real-time e-invoicing with RAMIS

The new format is the first step in a bigger change. Under the National e-Invoicing System announced in the 2026 Budget, the IRD is moving VAT-registered businesses to send invoice data in real time from their ERP systems to its RAMIS tax system through a secure Web API. Exporters were onboarded first, and the IRD expects full Web API integration by the end of 2026.

The circular also includes a concession: businesses approved by the Commissioner General for Web API integration before 1 July 2026 may treat the YYMMM_QQQQ_ part of the invoice number as optional, provided integration is completed by 31 December 2026. If you’re changing your invoicing system now, it’s worth building it so it’s ready to connect to RAMIS later, rather than paying for two rounds of changes.

How Microweb Global can help

Microweb Global builds and maintains custom software, ERP and POS systems for Sri Lankan businesses. We can help you:

• review your billing, POS or ERP system against the new format and list what needs to change;
• update invoice numbering, customer TIN validation, templates and receipts across every branch and channel;
• update online store and website invoices, including online payment flows; and
• prepare your system for real-time RAMIS Web API integration.

If you’re updating systems that hold customer data, it’s also a good time to prepare for the Personal Data Protection Act, whose core duties apply from 1 January 2027.

New VAT invoice format in Sri Lanka: frequently asked questions

Get your invoicing system compliant

Tell us which billing, POS or ERP system you use and we’ll tell you what needs to change, with a fixed-price quote for the work.

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Sources

• Circular SEC/2026/E/03: revised tax invoice format, Inland Revenue Department, 20 May 2026
• Public Notice SEC/PN/VAT/2026-03: National e-Invoicing System, Inland Revenue Department, 4 May 2026
• IRD extends VAT tax invoice format effective date to 1 October, Daily FC
• Is Sri Lanka ready for the new tax invoice format?, Tax Advisor