GST InvoiceNow for Small Businesses in Singapore: Dates, Who Is Affected and How to Prepare

A small trading company in Singapore sends forty invoices a month as PDF attachments. The bookkeeper types supplier invoices into the accounting software by hand. Nothing about this is wrong today. Under the GST InvoiceNow Requirement it will change, on a date that depends on the company's size. This article sets out the dates IRAS has published, what the change means in practice, and how a small team can prepare without a project.

One caution first. The dates and details below are taken from the IRAS page on the GST InvoiceNow Requirement as we read it in November 2026. Rules of this kind are adjusted. Confirm on the IRAS website before you plan around a date.

What the requirement is

InvoiceNow is Singapore's national e-invoicing network, built on the international Peppol standard. An invoice travels as structured data from the seller's system to the buyer's system through accredited access points.

The GST InvoiceNow Requirement adds one thing: GST-registered businesses use InvoiceNow solutions to transmit invoice data to IRAS. The tax authority receives the data from your system directly, in a standard format.

The published phases

IRAS describes a phased start:

• 1 November 2025. Newly incorporated companies that register for GST voluntarily.
• 1 April 2026. All new voluntary GST registrants.
• 1 April 2028. GST-registered businesses with annual supplies up to S$200,000.
• 1 April 2029. Those with annual supplies up to S$1 million.
• 1 April 2030. Those with annual supplies up to S$4 million.
• 1 April 2031. Those above S$4 million.

Two things stand out for small businesses. First, the smallest established GST registrants are scheduled earlier than the larger ones, so being small does not mean being last. Second, anyone registering voluntarily now is already inside the requirement from the day of registration.

IRAS also lists support for the transition: free InvoiceNow solution packages available until 31 March 2031, and a transition grant with amounts of S$1,000 or S$5,000 depending on the case. Check the conditions on the IRAS and IMDA pages, because eligibility has its own rules.

What changes in daily work

Sales invoices. You still create invoices in your accounting or invoicing software. The software sends the data through the network, and to IRAS. Customers on the network receive it in their system. Customers who are not can still get a PDF copy.

Purchase invoices. Suppliers on the network send invoices that arrive in your software as data. Less typing, fewer typing errors.

Accuracy matters earlier. Today a mistake in a tax code may be caught when the GST return is prepared. When invoice data goes to IRAS as it is issued, mistakes are visible sooner. The discipline moves from the quarter end to the day of invoicing.

Records. The invoice data in your system and the data transmitted must agree. Editing an invoice after sending it becomes a credit note and a new invoice, not a quiet correction.

A preparation list

1. Confirm your status and date. Are you GST-registered, compulsorily or voluntarily? Which turnover band are you in? Write down the date that applies.
2. Ask your software provider. Is the product an InvoiceNow-ready solution? Does it support transmission to IRAS? What does switching it on involve, and what does it cost?
3. If you invoice from spreadsheets or a word processor, choose a solution. This is the largest step for the smallest businesses. IMDA publishes the list of accredited solutions.
4. Clean customer and supplier records. Legal names, UEN numbers and addresses must be correct, because the network identifies businesses by them.
5. Check tax codes. Standard-rated, zero-rated, exempt and out-of-scope supplies must be coded correctly on every item you sell.
6. Fix the invoice process. Decide who issues invoices, who approves corrections, and how credit notes are raised. Write it on one page.
7. Test with one friendly customer and one supplier before the date, not on it.

Mistakes to avoid

• Waiting for the last phase date. Accounting firms and software providers will be busiest just before each deadline.
• Assuming a PDF by email is enough.
• Registering voluntarily for GST without counting this in. Voluntary registration now brings the requirement with it from the start.
• Running two sets of invoices, one in the system and one "real" one in a spreadsheet. The transmitted data is the record.
• Leaving it all to the bookkeeper. The data comes from sales: customer names, items, prices and tax treatment are set when the order is taken.

Where Polynusa fits, and where it does not

To be plain: Polynusa is not an accredited InvoiceNow solution, and it does not transmit invoices to IRAS. If you are a GST-registered business in Singapore, your invoicing for GST purposes should run through a solution on the IMDA list.

What a tool like Polynusa does is upstream of the invoice: keeping customer records, conversations, quotations and follow-up in one place, so the details that end up on the invoice are right the first time. Teams that sell in both Singapore and Indonesia often use it for the sales side and keep statutory invoicing in the accounting system their accountant chose. Plans are on the pricing page.

Summary

The GST InvoiceNow Requirement moves GST-registered businesses to structured e-invoices with data transmitted to IRAS, in phases published through 1 April 2031, with the smallest established registrants scheduled from 1 April 2028 and new voluntary registrants already covered. Preparation is mostly housekeeping: know your date, confirm your software, clean your records and tax codes, fix the invoice process and test early. Verify every date on the IRAS page before relying on it.

FAQ

Does GST InvoiceNow apply to a business that is not GST-registered?

The requirement described by IRAS is for GST-registered businesses. A business that is not registered for GST is not covered by it, although it may still choose to send and receive e-invoices through InvoiceNow. Check your registration status and the IRAS page before assuming either way.

Is a PDF invoice sent by email an InvoiceNow invoice?

No. A PDF is a picture of an invoice that a person reads. An InvoiceNow invoice is structured data sent over the Peppol network from one system to another, so the receiving system can read every field without retyping.

How long does it take a small business to get ready?

For a business already using cloud accounting software that supports InvoiceNow, switching it on and testing can take days. The slow part is cleaning customer records, tax codes and item descriptions so the data that goes out is right. Allow a few weeks for that.