InvoiceNow Mandatory by Apr 2031: Singapore GST Invoicing for Founders

Published: 7 October 2026 · Reviewed by Ray Tay, Co-Founder & Managing Director, VIVOS PTE. LTD. (ACRA Filing Agent FA20240323 · MOM EA Licence 24S2425)

If your Singapore company is not GST-registered, you issue a commercial invoice with no GST shown. If you are GST-registered, you must issue a tax invoice/basics-of-gst/invoicing-price-display-and-record-keeping/invoicing-customers) within 30 days showing the words “Tax Invoice,” your GST registration number, the 9% GST rate as of 2026, and the GST amount. On top of that, InvoiceNow e-invoicing is being phased in across GST-registered businesses, with mandatory cohorts rolling out through April 2031 as per IRAS.

TL;DR:

• Companies are required to issue a tax invoice within 30 days if they are GST-registered, including the words “Tax Invoice,” GST registration number, and GST details.
• A full tax invoice lists specific fields like invoice number, date, description, quantities, prices, and GST amounts, while a simplified invoice is allowed for totals under S$1,000.
• Zero-rated exports need proof of export within 60 days; otherwise, the transaction must be taxed at 9% and marked as “GST 0%”.
• InvoiceNow mandatory participation phases in from November 2025 to April 2031, with early connection enabling faster refunds and cleaner data.
• Proper record keeping, including five-year retention of invoices and supporting documents, is essential for compliance and smoother IRAS audits.

Table of Contents

• What must a Singapore invoice include?
• Do I need to charge GST on invoices?
• Simplified tax invoice rules and when receipts are acceptable
• Invoicing for exports and zero-rated supplies
• Is InvoiceNow mandatory? The GST e-invoicing timeline
• How to connect: the InvoiceNow technical checklist
• Record keeping, audits and practical compliance tips
• Setting up invoicing for a new Singapore company
• Common invoicing mistakes and how to fix them before an audit
• Why InvoiceNow is worth treating as an opportunity
• How we help with invoicing, GST registration and InvoiceNow readiness
• FAQ
• Sources

What must a Singapore invoice include?

The fields you need depend entirely on whether you charge GST. IRAS requires a full tax invoice from GST-registered suppliers for standard-rated supplies to other GST-registered businesses. That invoice must carry:

• The words “Tax Invoice” displayed prominently.
• Your business name, address, and GST registration number.
• An invoice number and invoice date.
• A description of the goods or services supplied.
• Quantity and unit price for each line item.
• The total amount payable excluding GST.
• The GST rate applied (9% as of 2026).
• The GST amount charged, shown separately from the price.
• The total amount payable including GST.
• Your customer’s name and address.
• Any discount offered, if applicable.

A simplified tax invoice is permitted when the total payable, GST included, does not exceed S$1,000. We cover the simplified format in detail in the next section.

If your company is not GST-registered, none of the GST fields apply. You issue a commercial invoice instead: business name and address, invoice number and date, description of goods or services, quantity, unit price, and total amount due. Never show a GST registration number or a GST amount on a commercial invoice. Many foreign founders inherit invoice templates from their home country that include a VAT or tax ID line by default, and leaving that field populated or mislabeled on a Singapore invoice creates confusion for overseas clients trying to reconcile their own tax filings, and can misrepresent your company’s registration status.

Where invoices are issued in a foreign currency, the GST amount itself must still be convertible to Singapore dollars using a consistent exchange rate, applied the same way invoice after invoice rather than switched between sources.

Do I need to charge GST on invoices?

You charge GST only once your company is GST-registered, and only on standard-rated supplies made to customers in Singapore.

Timing matters as much as the rate. According to IRAS’s GST General Guide, a tax invoice must be issued within 30 days from the time of supply, which is generally the earlier of the date goods are delivered or services performed, or the date payment is received. Missing that window does not cancel your GST liability, but it does create a compliance gap if IRAS reviews your records.

A few situations change what you need to issue:

• Zero-rated exports and certain exempt supplies do not strictly require a tax invoice, though many businesses issue one anyway for their own records, showing “GST 0%” clearly against the line item.
• Supplies to non-GST-registered customers for amounts under S$1,000 can use a simplified tax invoice instead of the full version.
• Customer-accounting rules apply to specific prescribed goods, such as mobile phones, memory cards, and off-the-shelf software, where the GST-registered buyer rather than the seller accounts for the output tax; these transactions carry their own invoice wording requirements.
• Credit notes and debit notes are required whenever a tax invoice needs correcting after issue, for example a price adjustment, a return, or a discount applied retroactively, and they must reference the original invoice number and show the GST adjustment separately.

Simplified tax invoice rules and when receipts are acceptable

When the total amount payable, GST included, is S$1,000 or less, you can skip the full tax invoice and issue a simplified version instead. A simplified tax invoice needs fewer fields but still has to function as valid GST documentation.

1. Show your business name, address, and GST registration number.
2. Show the invoice date and a serial invoice number.
3. Describe the goods or services supplied.
4. State the total amount payable, with wording such as “Price payable includes GST.”
5. Show the GST rate applied.

Receipts can stand in for an invoice in some retail and point-of-sale contexts, provided they carry:

• A serial number printed or generated automatically by the till or system.
• The GST registration number and the statement that GST is included in the price shown.

This format works well for retail counters, cafés, and low-value business-to-business sales where issuing a full nine-field tax invoice for a small purchase would be disproportionate. It does not replace the full tax invoice requirement once a GST-registered customer requests one for their own input tax claim.

Invoicing for exports and zero-rated supplies

Foreign founders running a Singapore company that bills overseas clients deal with zero-rating constantly, and it is one of the areas IRAS scrutinizes most closely during audits.

To substantiate a zero-rated export, IRAS requires documentary evidence tying the sale to an actual export out of Singapore:

• Export permits from Singapore Customs.
• Airway bills or bills of lading showing the goods left Singapore.
• Packing lists matching the invoiced goods.
• Proof of payment from the overseas customer.

A critical deadline sits inside this rule: if the goods are not exported within 60 days of the time of supply, the transaction must be standard-rated and GST accounted for at 9%, even if you originally invoiced at 0%. If you do issue a tax invoice for a zero-rated supply, mark the line clearly as “GST 0%” rather than leaving the GST field blank, which avoids ambiguity if the invoice is ever reviewed.

Pro Tip: Build a export-document folder per invoice number from day one, not retroactively. Reconstructing shipping evidence months later for an IRAS query is far harder than filing it as each shipment goes out.

Is InvoiceNow mandatory? The GST e-invoicing timeline

InvoiceNow is Singapore’s nationwide e-invoicing network, and GST-registered businesses are being brought onto it in stages rather than all at once. According to IRAS’s GST InvoiceNow Requirement page, mandatory participation is tied to your registration date and the scale of your business, with cohorts phased in from 1 November 2025, 1 April 2026, and then annually from April 2028 through April 2031.

The extension confirmed at Committee of Supply 2026 brings every GST-registered business onto InvoiceNow by April 2031. That timetable gives founders incorporating a new Singapore company now a reasonable window to build e-invoicing into their accounting setup from the start, rather than retrofitting it later.

Once a cohort date applies to you, the scope covers more than sales invoices:

• Sales invoices issued to GST-registered customers.
• Purchase invoices received from GST-registered suppliers.
• Credit notes and debit notes tied to GST-relevant transactions.
• Simplified invoices where the transaction still falls within InvoiceNow scope.

Certain registrants fall outside the mandate, including some overseas entities and businesses registered solely under reverse-charge rules. For everyone else, the submission deadline follows whichever comes first: the date you file your GST return, or the statutory due date for that return.

The practical upside is real. IRAS and IMDA frame mandatory submission as a way to shorten GST audit cycles and speed up refund processing, since invoice data reaches IRAS automatically rather than through a manual request during a review.

How to connect: the InvoiceNow technical checklist

Getting InvoiceNow-ready is a systems task, not a form to fill in. IMDA’s technical playbook lays out the mechanics, and most of the work happens inside your accounting software rather than on paper.

1. Check whether your accounting or ERP system is already listed as an InvoiceNow-Ready Solution, or engage an IMDA-accredited Access Point Provider to connect you to the Peppol network.
2. Register for a Peppol ID, which acts as your business’s address for sending and receiving e-invoices.
3. Enable the GST InvoiceNow submission feature inside your accounting solution, which embeds the mandatory data elements and a Document UUID into every invoice.
4. Add customer identifiers such as Customer UEN where the transaction requires one, so the receiving party’s system can match the invoice automatically.
5. Set up internal controls: immutable invoice records, human-readable exports for audit purposes, and a Check GST Register API check to confirm a customer’s GST number before an invoice goes out.
6. Schedule a recurring extraction and reconciliation, weekly works well, comparing what left your accounting system against what InvoiceNow confirms was transmitted.

Pro Tip: If you run an online storefront alongside invoiced B2B sales, map how your point-of-sale or e-commerce platform exports transaction data before your InvoiceNow cohort date arrives; a Shopify setup guide for Singapore merchants is a useful reference for aligning checkout data with your accounting feed.

We go deeper on the implementation side, including common connection pitfalls, in our guide to e-invoicing in Singapore.

Record keeping, audits and practical compliance tips

GST invoices and the documents behind them need to survive longer than most founders expect. IRAS requires that invoices and supporting records be kept for at least 5 years, and Singapore Customs applies the same retention period to trade documents tied to imports and exports.

Electronic storage is acceptable, which removes the need for a physical filing cabinet, but only if the records stay retrievable and legible for the full retention period.

• Keep a structured electronic repository indexed by invoice number and date, not loose email attachments.
• Store export evidence alongside its matching invoice, not in a separate shipping folder.
• Back up records off-site or to cloud storage, since a lost hard drive during year four of a five-year retention period creates a real compliance gap.

Our bookkeeping and compliance service sets this indexing up from month one, so records are audit-ready without a scramble when IRAS sends a query.

Setting up invoicing for a new Singapore company

Founders incorporating from overseas tend to build invoicing processes in the wrong order, often designing templates before deciding on GST registration timing. This sequence avoids the rework.

1. Decide whether to register for GST voluntarily or wait until compulsory registration applies, since your registration date determines both your invoicing format and your InvoiceNow cohort.
2. Build three invoice templates in advance: a full tax invoice, a simplified tax invoice, and a commercial invoice for use before GST registration.
3. Choose an InvoiceNow-Ready accounting solution or confirm your Access Point Provider, then register for a Peppol ID and switch on GST submission before your mandatory cohort date.
4. Set up export-evidence capture as a routine step in your shipping or delivery process, not an afterthought triggered by an audit letter.
5. Schedule monthly reconciliation between invoices issued, GST collected, and bank receipts, catching mismatches while they are still easy to trace.

We incorporate Singapore companies for foreign founders, handling nominee resident director, registered address, corporate secretary, GST registration, and bookkeeping, and we offer setup support in multiple jurisdictions for founders expanding their businesses.

Common invoicing mistakes and how to fix them before an audit

Most GST issues IRAS flags trace back to a small set of recurring errors, and almost all of them are cheaper to fix now than during a review.

• Tax invoices missing one of the required fields, most often the GST registration number or the separated GST amount.
• Charging GST before registration is confirmed, or forgetting to charge it once registration takes effect.
• Export evidence that was never filed, or filed under the wrong invoice number.
• Exchange rates applied inconsistently across invoices to the same customer.
• Missing an InvoiceNow submission deadline once your cohort date has passed.

Penalties for incorrect GST returns can include financial penalties and back-tax assessments, and IRAS operates a Voluntary Disclosure Programme that reduces penalties for businesses that correct errors before IRAS detects them independently.

Pro Tip: Run a quarterly self-check against your own invoice checklist, comparing a sample of invoices against the mandatory field list, rather than waiting for your annual filing to surface problems.

Why InvoiceNow is worth treating as an opportunity

InvoiceNow is often framed purely as a compliance deadline, but businesses that connect early get cleaner data, faster GST refunds, and fewer manual corrections at filing time.

We set up new Singapore companies for foreign founders, covering nominee resident director, registered address, corporate secretary, GST registration, and bookkeeping, with similar services available in other jurisdictions. Our recommendation is to connect to InvoiceNow as part of your initial accounting setup, not as a separate project once your cohort date is already close.

How we help with invoicing, GST registration and InvoiceNow readiness

Getting invoice templates, GST registration timing, and InvoiceNow onboarding right at the same time is harder for a founder managing it alone from overseas than for a team that does this setup daily. We handle foreign-founder and local incorporation, corporate secretary duties, GST registration and filing, bookkeeping and compliance, and ongoing accounting, so your invoicing process is built correctly before your first GST return is due rather than patched together afterward. We also provide nominee resident director, registered address, corporate secretary, GST registration, and bookkeeping support for founders expanding in multiple jurisdictions. Check our pricing and packages to see what fits your stage, or review our GST registration and filing support if your registration date is approaching.

FAQ

What are the requirements for an invoice?

A Singapore invoice needs your business name and address, an invoice number and date, a description of goods or services, quantity, and the total amount due. If you are GST-registered, additional fields apply, including “Tax Invoice,” your GST number, the GST rate, and the GST amount.

What do you legally have to have on an invoice?

At minimum, every invoice needs a business name, address, invoice number, date, description of the supply, and total amount payable. A GST-registered business must also add the words “Tax Invoice,” its GST registration number, the GST rate of 9%, and the GST amount shown separately, as set out in IRAS’s invoicing guidance.

Can I issue an invoice without GST?

Yes, if your company is not GST-registered you issue a commercial invoice with no GST shown at all, and you never display a GST registration number or GST amount. Once you register for GST, you switch to issuing tax invoices that include the GST rate and amount on standard-rated supplies.

Can individuals issue invoices?

Individuals operating as sole proprietors or self-employed persons can issue invoices, and the same GST rules apply based on registration status. A sole proprietor who crosses the GST registration threshold must issue tax invoices exactly like a company, following the same field requirements IRAS sets for registered businesses.

Sources

• InvoiceNow technical playbook (IMDA)

Recommended

• GST Registration Singapore: Guide for Business Owners
• Singapore GST Guide 2025