This article is accurate as of 13 October 2026. GST InvoiceNow rules, solution lists, grant terms and software support dates are set by IRAS, IMDA and software vendors and can change at any time. It is general information, not tax or IT advice; check the official sources listed at the end before making a decision.
TL;DR
The rule: under GST InvoiceNow, IRAS requires invoice data to be sent through an InvoiceNow-Ready Solution. Software that only prints or emails PDFs does not meet it on its own.
Check first: look up your exact software and version on IMDA’s InvoiceNow-Ready Solution Provider list at go.gov.sg/invoicenowirsp.
Three routes: upgrade the software you have, bolt a separate InvoiceNow tool onto it, or switch to a system with InvoiceNow built in. Each has a different cost in money and in re-typing.
Your history must survive. IRAS requires records to be kept for five years, so plan how the old data stays readable before you retire anything.
Pick your cut-over date carefully: the first day of a GST quarter or financial year is the cleanest.
Existing GST-registered businesses join between 1 April 2028 and 1 April 2031, but grants and free packages reward moving earlier.
There’s a PC in the corner of the office that nobody is allowed to switch off.
It runs the accounting program. It has run the accounting program for eleven years. The person who set it up left in 2019, the backup goes to a thumb drive on Fridays (most Fridays), and when the accountant needs the data at year end, someone emails her a file with “COPY DO NOT OPEN” in its name.
It works. That’s the problem. Nothing about it is broken enough to fix, so it never gets fixed.
GST InvoiceNow changes that. Once your business reaches its implementation date, IRAS expects your invoice data to arrive as structured data through approved software, not as a PDF and a phone call. IMDA says more than 63,000 businesses are already on the InvoiceNow network, and it expects about 90,000 more to join as the GST requirement rolls out. For a lot of them, the first question is whether the program on that corner PC can come along.
This guide helps you answer that honestly, compare your options, and move without losing ten years of history.
1. What GST InvoiceNow asks of your software
IRAS’s e-Tax Guide is direct: GST-registered businesses that come under the requirement must use InvoiceNow-Ready Solutions to submit invoice data to IRAS. These are accounting and finance systems that can send invoices over the InvoiceNow (Peppol) network, and the transmission to IRAS happens by API, system to system.
That rules out three common set-ups on their own:
A program that only produces PDFs, which you then email or print.
An Excel or Word invoice template, however tidy.
A version of a program that has an InvoiceNow-ready edition, if you are still running an older version that isn’t on the list.
Larger businesses that run their own in-house or customised systems, which won’t appear on IMDA’s list, can connect through an IMDA-accredited Access Point Provider instead. That route usually involves integration work.
If your business registered for GST before 2026, your implementation date falls between 1 April 2028 and 1 April 2031, depending on your total annual supplies. (Our guide to what InvoiceNow is has the full phase table.)
2. The 8-question test: can your software handle GST InvoiceNow?
Answer these with whoever looks after your accounts. The first question matters most.
# | Question | Yes / No |
|---|---|---|
1 | Is our exact software and version on IMDA’s InvoiceNow-Ready Solution Provider list (go.gov.sg/invoicenowirsp)? | ☐ |
2 | Has our vendor confirmed in writing what it costs to switch on InvoiceNow and GST submission for our version? | ☐ |
3 | Is the vendor still releasing updates for our version, including the latest GST changes? | ☐ |
4 | Can the software send and receive e-invoices itself, without someone re-typing them into another tool? | ☐ |
5 | Does it record purchase bills with the supplier’s details, tax code and GST amount for each line or invoice? | ☐ |
6 | Can more than one person use it at the same time, from wherever they work? | ☐ |
7 | Is the computer it runs on still receiving security updates, and is the data backed up automatically, off-site? | ☐ |
8 | If that computer failed tomorrow, could we restore the books within a day? | ☐ |
How to read your score. If question 1 is a no, your current software cannot meet the requirement on its own, whatever the other answers are. If question 1 is a yes but you answered no to three or more of questions 2 to 8, the software can technically comply, but the cost of keeping it may be higher than it looks.
Question 7 is more pressing than it sounds. Windows 10 reached the end of support on 14 October 2025. Businesses that pay for Extended Security Updates reach the end of Year 1 on 13 October 2026, and Year 2 costs US$122 per device, double the Year 1 price. If the PC running your accounting program is on Windows 10, its upgrade and your software decision are now the same conversation.
3. Your three options, side by side
Once you know where your software stands, there are three realistic routes.
1. Upgrade what you have | 2. Bolt on a separate InvoiceNow tool | 3. Switch to a system with InvoiceNow built in | |
|---|---|---|---|
What it means | Move to a newer edition of your current software that is on IMDA’s list | Keep your accounting program; send and receive e-invoices through a separate portal or connector | Move your books to accounting or ERP software that sends InvoiceNow and GST data itself |
Works when | Your vendor has an InvoiceNow-ready edition and you’re happy with the software | You need a stop-gap, or have very few invoices | Your version isn’t on the list, or the PC, backups or multi-user access are already a problem |
Upfront effort | Low to medium: upgrade, plus re-testing | Low: sign up and register a Peppol ID | Medium: set-up and data migration |
Ongoing effort | Same as today | High: each invoice is recorded twice, once in each system | Lower: one entry per transaction |
Risk to watch | Upgrade fees, and being tied to the same PC | The two systems drift apart, and your GST return has to reconcile them | Migration mistakes if rushed; plan the cut-over date |
Option 1 is the right call more often than vendors of new software admit. If your vendor has a listed, supported edition and your team is comfortable, upgrading is the least disruptive route. Get the price for your version in writing, and ask whether it covers receiving invoices as well as sending them.
Option 2 works best as a bridge. IMDA’s free packages include simple e-invoicing portals, and they are a genuine help to a business with a handful of invoices a month. For everyone else, the cost is people’s time: every sales invoice and supplier bill has to exist in both places, and at the end of the quarter someone has to make sure they still agree. (Our comparison of the free GST InvoiceNow packages explains the different kinds of “free”.)
Option 3 costs the most effort once, and the least after that. It makes sense when the answer to question 1 is no, or when the PC, backups and single-user access are problems you would want to solve anyway. Sections 5 and 6 cover how to do it without losing your history.
4. Four costs that don’t show up on a quote
When you compare the three routes, the software price is usually the smallest number. These are the ones that catch owners out:
Re-typing time. A bolt-on that means entering 200 invoices a month twice is 200 extra entries, every month, by someone you’re paying.
Reconciliation at GST time. Under GST InvoiceNow, the invoice data you send to IRAS should tally with your GST return. Two systems means two sets of numbers to match every quarter.
The single point of failure. One PC, one data file, one person who knows the password. The cost appears all at once, on the day it fails.
The vendor’s clock. Older editions stop receiving updates. When a GST change arrives and your version isn’t patched, you upgrade in a hurry, on the vendor’s terms.
5. Switching without losing your history
The fear that keeps most businesses on old software is losing years of records. IRAS’s record-keeping rule is clear: under the Income Tax Act and the GST Act, you must keep your records for five years. You can keep them electronically without asking IRAS for approval, as long as they remain complete, accurate and available. Failing to keep proper records is an offence, with fines of up to S$5,000, and up to S$10,000 for a repeat conviction.
That doesn’t mean you need to move ten years of transactions into the new system. Most businesses move a clean starting position, and archive the rest in a form they can still open.
Move into the new system | Archive from the old system (keep for at least 5 years) |
|---|---|
Chart of accounts, mapped to the new structure | Full general ledger and journal listings for each past year |
Customers and suppliers, with UEN and Peppol ID where known | Sales and purchase invoice listings, with GST, by period |
Items, prices and tax codes | Past GST returns and the reports used to prepare them |
Trial balance at the cut-over date (opening balances) | Year-end financial statements and tax computations |
Open customer invoices and unpaid supplier bills | Bank reconciliations and fixed asset registers |
Stock on hand, with quantities and costs | A full backup of the old data file, plus a copy of the software installer |
Export the archive reports to PDF and Excel as well as keeping the original data file. A data file is only useful if you still have a working copy of the software and a computer that can run it. PDFs and spreadsheets will still open in five years.
If your business is moving to GST InvoiceNow on the purchase side too, our article on supplier invoices explains what IRAS expects for bills you receive.
6. A 6-week cut-over plan
The cleanest cut-over date is the first day of a GST quarter, and better still the first day of your financial year. That way, every GST return and every set of accounts comes from one system only. For a business on calendar quarters with a December year end, 1 January 2027 does both.
Week | Focus | Done when |
|---|---|---|
Week 1 | Decide and choose | Route chosen; new system trial started; cut-over date agreed with your accountant |
Week 2 | Clean the old books | Bank accounts reconciled; duplicate customers, suppliers and items merged; old unpaid items written off or chased |
Week 3 | Set up the new system | Company details, GST registration, tax codes, chart of accounts and users set up; Peppol ID registered |
Week 4 | Load master data | Customers, suppliers and items imported and spot-checked against the old system |
Week 5 | Test | A few real invoices and bills entered in both systems; GST and totals match |
Week 6 | Go live and archive | Opening balances, open invoices, unpaid bills and stock loaded at the cut-over date; old system set to read-only; archive saved in two places |
Keep the old system running in read-only mode until your first GST return from the new system has been filed and checked. If the switch happens close to a filing deadline, IRAS lists “purchase of a new accounting software or IT system” as an acceptable reason for a GST filing extension of up to two weeks. You need the tax invoice for the software, and the request must reach IRAS at least five working days before the due date, so don’t treat it as a plan.
Avoid cutting over in the middle of year-end closing. If your corporate tax return is still being prepared, finish that first.
7. Don’t wait for your implementation date
A mandate date of 2029 or 2030 can feel like permission to wait. Two things argue against it.
First, the help is front-loaded. IMDA’s free InvoiceNow packages run to March 2031, but the transition grants have their own conditions and deadlines, several of which fall before many businesses’ own implementation dates. Our article on GST InvoiceNow grant deadlines sets them out, and our EDGE Grant guide covers support for wider software spending now that PSG has ended.
Second, the switch is easier when nothing is on fire. A migration planned around a quiet quarter, with the old system still working, is a very different project from one forced by a failed PC or a vendor ending support.
Frequently asked questions
How do I know if my accounting software is InvoiceNow-ready?
Check IMDA’s InvoiceNow-Ready Solution Provider list at go.gov.sg/invoicenowirsp, and look for your exact edition and version, not just the brand. If it is listed, ask your provider to switch on InvoiceNow and confirm whether GST submission to IRAS is included.
Can I keep my desktop accounting software under GST InvoiceNow?
Yes, if your version is on IMDA’s list or your vendor offers a listed upgrade. If it isn’t, you will need a separate InvoiceNow-Ready Solution or a switch, because IRAS requires invoice data to be submitted through one.
Can I keep my old software and use a free InvoiceNow portal?
You can, but every invoice then has to be recorded in both systems, and your GST return must still reconcile with the data sent to IRAS. It suits businesses with few invoices, or as a short-term bridge.
How long must I keep records from my old accounting system?
At least five years, under the Income Tax Act and the GST Act. You can keep them electronically, as long as they stay complete, accurate and available when IRAS asks for them.
Do I need to move all my old transactions into the new system?
Usually not. Most businesses move master data, opening balances, open invoices, unpaid bills and stock at a cut-over date, and archive the old ledgers and reports separately for at least five years.
When is the best time to switch accounting software?
The first day of a GST quarter, and ideally the first day of your financial year, so each GST return and each year’s accounts come from one system.
Can I get more time to file my GST return if I’m changing software?
IRAS may grant up to two weeks for the purchase of new accounting software or an IT system. You need the software’s tax invoice, and the request must be made at least five working days before the due date.
When does GST InvoiceNow apply to my business?
New voluntary GST registrants are already covered. Existing GST-registered businesses are phased in from 1 April 2028 to 1 April 2031, based on total annual supplies. IRAS notifies each business of its date.
Where AveriWorks fits
If your answers to the 8-question test pointed to option 3, AveriWorks is built for that move. It is a cloud ERP for Singapore businesses, so your team works in a browser from wherever they are, and there’s no office PC to keep alive. Sales, purchasing, inventory and accounting post to one ledger, and InvoiceNow and GST InvoiceNow are built in, so each invoice is entered once.
On the paid plans, a guided import wizard brings in your chart of accounts, customers, suppliers, items and opening balances from CSV or Excel, along with your trial balance, open invoices and stock. The free Starter plan includes accounting, unlimited InvoiceNow and GST InvoiceNow, and AveriWorks is on IMDA’s list of free-of-charge InvoiceNow packages for GST-registered businesses.
Start free at averiworks.com/register, or compare plans at averiworks.com/pricing.
Sources
All sources accessed on 13 October 2026. This article is accurate as of 13 October 2026.
IRAS, e-Tax Guide: Adopting GST InvoiceNow Requirement (2nd edition, 9 March 2026). https://www.iras.gov.sg/docs/default-source/e-tax/etaxguide_gst_invoicenow_requirement.pdf
IRAS, GST InvoiceNow Requirement. https://www.iras.gov.sg/taxes/goods-services-tax-(gst)/gst-invoicenow-requirement
IRAS, Record Keeping Guide for GST-Registered Businesses (12th edition, 30 January 2026). https://www.iras.gov.sg/media/docs/default-source/e-tax/record-keeping-guide-for-gst-registered-businesses.pdf
IRAS, GST filing due dates and requests for extension. https://www.iras.gov.sg/taxes/goods-services-tax-(gst)/filing-gst/gst-filing-due-dates-and-requests-for-extension
IMDA, Committee of Supply 2026 factsheet. https://www.imda.gov.sg/resources/press-releases-factsheets-and-speeches/factsheets/2026/committee-of-supply-2026
IMDA, InvoiceNow. https://www.imda.gov.sg/invoicenow
IMDA, InvoiceNow-Ready Solution Provider list. https://go.gov.sg/invoicenowirsp
TechRepublic, Windows 10 ESU cheat sheet: cost, eligibility and coverage (18 August 2026). https://www.techrepublic.com/article/news-windows-10-esu-cheat-sheet/
Help Net Security, Microsoft gives Windows 10 users an unexpected extra year of free security updates (26 June 2026). https://www.helpnetsecurity.com/2026/06/26/microsoft-windows-10-free-security-updates-esu-program/
AveriWorks, Pricing. https://averiworks.com/pricing