InvoiceNow in Singapore: What GST-Registered Businesses Should Do After the IRAS Letter

So even if your date is 2029 or 2030, the planning starts now. This guide covers how to read your date, which route fits your setup, and what to clean up in your billing data first. It is general guidance, not tax advice. Check your own case with IRAS or your tax adviser.

When does your business have to start?

IRAS phases the requirement by your total annual supplies. That means standard-rated, zero-rated and exempt supplies (Box 4 of the GST return) across the accounting periods ending in calendar year 2025.

Smaller businesses go first on purpose. The Government said it will prioritise smaller firms in the early years because most of them use off-the-shelf accounting software that is already InvoiceNow-Ready, while larger firms need more time to fit the change into their enterprise systems.

Two groups are excluded: overseas entities, including overseas vendors registered under the OVR regimes, and businesses that are GST-registered only because of the reverse charge rules.

No letter yet? IRAS says some businesses, for example those without GST returns for periods ending in 2025, will get their date later. You can also work it out yourself with the GST InvoiceNow Implementation Date Calculator on the IRAS page.

Step 1: Confirm your date and who owns the project

Find the IRAS letter, check the date against the table, and write it down where your finance and IT people will both see it. Then name one owner. In most SMBs that is the finance lead, with help from whoever manages your accounting or billing software. Work back from the date: if onboarding can take up to a year, a 1 Apr 2028 business should be choosing its route in early 2027 at the latest.

Step 2: Work out which route you are on

IRAS describes two routes, and which one you are on depends on how you invoice today.

Off-the-shelf accounting or billing software. Check whether your product is on IMDA's list of accredited InvoiceNow-Ready Solutions. If it is, your provider will help you register a Peppol ID (based on your UEN) in the SG Peppol Directory, and you then switch on the GST InvoiceNow submission feature. For many small businesses this is mostly a settings and data job.

Your own in-house or custom system. If you invoice from an ERP you have customised, a system built for you, or a mix of tools, you need an IMDA-accredited Access Point Provider. You get a Peppol ID through them, and then work with them to connect your system to IRAS. This is where the 3 months to a year comes from.

Watch for the mixed cases. Plenty of businesses run accounting in one package but raise invoices from a booking system, an ecommerce store, a POS or a spreadsheet. Every place that issues an invoice needs a path into InvoiceNow, not just your main ledger.

Step 3: Map every place an invoice is created

Before talking to any provider, list:

• Every system that issues sales invoices, credit notes or debit notes
• Who raises them and roughly how many each month
• Whether the invoice is created in your accounting software or copied into it later
• Any manual steps, such as invoices typed from a quote, edited PDFs, or exports to Excel

This list tells you how big the job is. If everything already flows from one InvoiceNow-Ready package, it is small. If invoices come from three places and get re-keyed, that is the real project.

Step 4: Clean the data that goes on the invoice

E-invoices are structured data, so gaps that a PDF could hide will show up. Check:

• Customer records. Correct legal names, UENs where they apply, and addresses, with duplicates merged.
• GST codes. Each item and service mapped to the right tax treatment (standard-rated, zero-rated, exempt), with no free-text tax lines.
• Item and service master. Consistent descriptions and units, not one-off text typed on each invoice.
• Credit notes. Linked to the original invoice rather than issued as negative invoices with no reference.
• Numbering. One clear numbering sequence per issuing system.

IRAS also points out that InvoiceNow-Ready Solutions can add checks, for example flagging wrongful GST charged by suppliers that are not GST-registered. Ask your provider which of these checks they offer.

Step 5: Use the support while it is available

IRAS lists a GST InvoiceNow Transition Grant of S$1,000 for SMEs (annual supplies up to S$4 million) and S$5,000 for larger businesses. Free-of-charge solution packages with basic e-invoicing are available up to 31 March 2031. Check IMDA's InvoiceNow grants page for eligibility before you sign anything, since the rules sit with IMDA.

Step 6: Test before your date, not on it

Ask your provider for a test run with real but low-risk invoices. Confirm the invoice data reaches IRAS, that credit notes behave, and that your finance team can see what was sent. Plan the switch for a quiet week, not your month-end close.

Common mistakes to avoid

• Treating the date as the start date. The date is when you must already be submitting.
• Only fixing the main accounting system. Side systems that issue invoices get missed.
• Re-keying invoices into the InvoiceNow tool. It works on day one and creates errors by month three.
• Leaving it to one person. Finance knows the tax codes, IT knows the systems. You need both.

Where Ascent24 can help

Ascent24 is not an Access Point Provider and does not sell an InvoiceNow-Ready Solution. Where we help is the integration work around them: mapping where your invoices come from, cleaning customer and item data, and connecting custom or legacy billing, ecommerce or ERP systems to the Access Point you choose. If you are planning your InvoiceNow move, contact us at info@ascent24.io. If you also invoice in the Gulf, see our guides on Saudi e-invoicing Wave 25 and getting your billing and ERP data ready for UAE e-invoicing.

FAQs

Does every GST-registered business in Singapore need InvoiceNow?

Yes, apart from a few exclusions. All GST-registered businesses must submit invoice data to IRAS through InvoiceNow, phased from 1 Apr 2028 to 1 Apr 2031 for existing registrants. Overseas entities, including OVR-registered overseas vendors, and businesses registered only because of reverse charge are excluded.

How do I find my InvoiceNow implementation date?

IRAS has been notifying GST-registered businesses registered before 2026 since mid-2026. You can also check it with the GST InvoiceNow Implementation Date Calculator on the IRAS GST InvoiceNow Requirement page. It is based on your total annual supplies in accounting periods ending in 2025.

How long does InvoiceNow onboarding take?

IRAS says it can take as little as 3 months, and most businesses complete setup within a year, depending on how ready their systems are.

Do I need an Access Point Provider?

If you use an accredited InvoiceNow-Ready Solution, your solution provider handles the connection. If you use an in-house or custom system, you need to work with an IMDA-accredited Access Point Provider to connect it to IRAS.

Is there funding for InvoiceNow?

IRAS lists a GST InvoiceNow Transition Grant of S$1,000 for SMEs and S$5,000 for larger businesses, plus free-of-charge solution packages up to 31 March 2031. Eligibility is set by IMDA.

Sources

• IRAS, GST InvoiceNow Requirement (phases, exclusions, routes, onboarding time, grants): https://www.iras.gov.sg/taxes/goods-services-tax-(gst)/gst-invoicenow-requirement
• IRAS, Committee of Supply 2026: Extension of GST InvoiceNow Requirement to All GST-registered Businesses by April 2031 (26 Feb 2026): https://www.iras.gov.sg/news-events/newsroom/committee-of-supply-2026--extension-of-gst-invoicenow-requirement-to-all-gst-registered-businesses-by-april-2031