InvoiceNow e-invoicing FAQ for Singapore businesses

Once businesses get past the headline rollout dates, the questions become much more practical.

Does this only matter if both sides are already on InvoiceNow? What happens if the business still sends PDFs? Do credit notes count? And if invoice data is being sent to the IRAS, does that change the usual GST recordkeeping work?

The requirement itself is straightforward on paper, but the day-to-day questions are the ones businesses actually need answered. This FAQ was made using information from various Inland Revenue Authority of Singapore (IRAS) sources for you.

What is InvoiceNow? 

InvoiceNow is Singapore’s national e-invoicing network, built on the PEPPOL standard. In everyday terms, it lets businesses send and receive invoice data in a structured format instead of relying only on PDFs, scans, or manual entry. The IRAS is linking this to GST administration as part of its wider move toward more digital tax processes.

What is the GST InvoiceNow requirement? 

The requirement states that certain GST-registered businesses will need to transmit invoice data to the IRAS using an InvoiceNow-ready solution. Every GST-registered business will not be brought under the requirement at the same time. The IRAS is introducing it in phases.

Who has to comply, and when?  

The IRAS has set a phased rollout.

It went into effect on 1 November 2025 for all companies that voluntarily register for GST within six months of incorporation.

As of 1 April 2026, it applies to all new voluntary GST registrants.

From 1 April 2028 onward, it expands to new compulsory GST registrants and then to existing GST-registered businesses in bands based on annual supplies, finishing with businesses above S$4 million on 1 April 2031.

The IRAS also says existing GST-registered businesses will be informed of their applicable date by mid-2026, and it provides a calculator in the meantime.

Are any businesses excluded? 

Yes. The IRAS excludes overseas entities, including overseas vendors under the Overseas Vendor Registration (OVR) regimes, and businesses that are liable to register for GST wholly because of the Reverse Charge regime. The IRAS FAQ on e-invoicing also makes it clear that a business already registered under the normal GST regime does not fall outside the requirement simply because reverse charge transactions form part of its GST position.

Is this only about sales invoices? 

No. That is one of the first assumptions that usually needs correcting.

The IRAS says the data to be transmitted covers transactions reported in the GST return, including purchases, standard-rated supplies, zero-rated supplies, exempt supplies, standard-rated purchases, and zero-rated purchases. So this is not only about invoices going out to customers. It covers all data that supports GST reporting.

What kinds of documents fall within the scope? 

The IRAS takes a fairly broad approach here. The requirement covers invoice data from invoices and equivalent documents that function as a bill for payment or an adjustment to one. The examples it gives include tax invoices, simplified tax invoices, sales invoices, serially numbered receipts, debit notes, and credit notes.

Do credit notes and debit notes need to be included too? 

Yes, though this is one of the areas where the details matter.

The IRAS already includes debit notes and credit notes in the list of relevant documents. In the IRAS FAQ on e-invoicing, it goes further and explains situations such as volume rebates, where businesses should identify the original tax invoices where possible. It also says a debit note should not be used in place of a tax invoice for a standard-rated supply made to a GST-registered customer. Even a credit note that does not involve a GST adjustment may still need to be transmitted.

What if one invoice includes different GST treatments? 

That is allowed. The IRAS says a single invoice can contain line items with different GST category codes. So a business does not need to split one invoice into separate documents just because some items are standard-rated and others are zero-rated or exempt.

Are any transactions outside the requirement? 

Yes. The IRAS says the following do not need to be transmitted:

• Certain deemed supplies with no underlying purchase or sale

• Reverse charge transactions

• Exempt financial services

• Exchange or loan of digital payment tokens

• Import permits for imported goods

So while the requirement is broad, it is not a “send every GST-related record” rule.

What if the customer is not on InvoiceNow? 

The data may still need to be transmitted.

The IRAS explains that invoice data can still be submitted through the solution-extracted submission method for invoices issued outside the InvoiceNow network. That includes paper and PDF invoices issued to customers who are not on InvoiceNow, including individuals. So the requirement is not limited to transactions where both parties are already exchanging PEPPOL invoices directly.

Can businesses still issue PDFs or paper invoices? 

Yes, but businesses need to be careful once PEPPOL invoices are also part of the process.

The IRAS says issuing PDFs or paper copies remains a business decision. But if a supplier issues a PDF or paper invoice after already issuing a PEPPOL invoice for the same transaction, that later copy should be treated as a duplicate. The customer should take care not to make a duplicate input tax claim.

When does invoice data need to be sent to the IRAS? 

The IRAS ties the deadline directly to the GST return. The data must be transmitted by the earlier of two dates: the date the relevant GST return is filed, or the filing due date of that GST return. That means the submission is not something businesses can leave until well after the return cycle has passed.

How is the transaction date determined? 

That depends on the transaction.

For supplies where an invoice is or will be issued, the IRAS says the transaction date is the issuance date of the document. In other cases, it may be the date the transaction is posted into the accounting system. For purchases, the transaction date may depend on the basis used for claiming input tax, such as the invoice date or the posting date in the system where allowed. It matters because it determines which GST return period the data belongs to.

What happens if the invoice is in a foreign currency? 

The IRAS says invoice data relevant to GST reporting must be converted into Singapore dollar equivalents before submission if the original invoice is in a foreign currency. The exchange rate itself does not need to be included in the data transmitted. This is especially relevant for exporters, regional service providers, and businesses billing overseas counterparties.

Can some transactions be submitted on an aggregated basis? 

Yes. The IRAS allows aggregation for some categories, including supplies made through point-of-sale systems, supplies where simplified tax invoices or serially numbered receipts are issued, and petty cash purchases. That makes the process more workable for businesses dealing with high volumes of smaller-value transactions.

How does self-billing fit in? 

The IRAS deals with self-billing separately. Because self-billed invoices are issued outside the InvoiceNow network, they are transmitted using the solution-extracted submission method. The IRAS FAQ on e-invoicing explains how the customer-cum-issuer and supplier-cum-recipient handle relevant data under different transaction types. If self-billing forms part of your current process, this is one area where it is worth reading the IRAS instructions carefully rather than assuming the normal invoice flow applies unchanged.

What details are needed if the customer is not on InvoiceNow? 

The IRAS still expects certain data fields to be captured for submission, including customer name, customer UEN, and customer address where relevant. The IRAS FAQ also notes that if the customer is a non-GST-registered individual, “NA” may be used for some fields such as Customer Name and Customer UEN. That is a useful clarification for businesses dealing with both businesses and consumers.

How does a business get started with InvoiceNow e-invoicing? 

For businesses using off-the-shelf accounting or finance software, the IRAS says the typical steps are to choose an InvoiceNow-ready solution, register in the SG PEPPOL Directory using the UEN, obtain a PEPPOL ID, and activate the GST InvoiceNow submission feature. For in-house enterprise systems, the process is more involved because the business needs to work with an IMDA-accredited Access Point Provider and set up the connection properly.

How long does onboarding usually take? 

The IRAS says many common accounting and finance solutions already support InvoiceNow or are compatible with it, so in some cases setup may mainly involve activation. For businesses using in-house systems, the IRAS says the connection and testing process can take as little as three months, but some businesses have taken as long as an year to onboard.

Does InvoiceNow replace GST recordkeeping? 

No. The IRAS is clear that the existing recordkeeping requirements still apply. Using InvoiceNow does not remove the need to keep proper GST records. That distinction matters because sending invoice data to the IRAS does not automatically reduce a business’s recordkeeping responsibilities.

Do supporting documents have to be sent to the IRAS too? 

No. The IRAS says supporting documents do not need to be transmitted as part of the invoice data submission. But the business must still keep those documents and produce them if requested later. So the transmission requirement and the record-retention requirement remain separate.

Can this software help flag GST issues? 

To some extent, yes. The IRAS has published guidance on recommended validation features for erroneous GST charges. One example it gives is a validation check at the point of invoice creation or issuance, so the business can be alerted if GST might have been charged incorrectly, such as where a supplier’s GST registration details are invalid. That does not turn the software into the final decision-maker, but it does show how the system can support stronger controls.

What happens if errors are made? 

The IRAS says businesses remain responsible for their GST obligations, including invoicing correctly and filing accurate GST returns. It also points businesses to the Voluntary Disclosure Programme, which may reduce or waive penalties where the relevant conditions are met. The IRAS has also said its enforcement approach will be calibrated during the initial onboarding phases for genuine mistakes that are not due to negligence or made without reasonable excuse.

Is there any support for adoption? 

Yes. The IRAS says grants and free solution packages are available for eligible businesses. It has also announced support for SMEs and for larger businesses that adopt early, along with free-of-charge solution packages through participating providers across the early years of implementation.

What businesses should keep in mind 

A few points matter more than the rest.

InvoiceNow is not simply a new way to send invoices. It is also part of how invoice data will move to the IRAS. The rollout is phased, so businesses need to track their own implementation date. The scope is wider than many expect, because it includes more than standard invoices. Simultaneously, not every transaction falls within it, and some categories can be aggregated. While the requirement changes how data is transmitted, it does not replace the need to keep supporting records properly. The businesses that will handle this transition the smoothest are usually the ones that prepare their workflows early, rather than waiting until the date gets close.