How to Get Your Suppliers Onto InvoiceNow Before the GST Mandate: A 90-Day Campaign

Getting your suppliers onto InvoiceNow is a procurement campaign, not an IT project, and it works best run in waves rather than as one blanket email blast. The sequence that actually moves counterparties: check the SG Peppol Directory to find out who is already registered (usually more than you expect), rank the rest by how many invoices they send you each month, then approach the top 20 suppliers individually with a named contact and a date, and the long tail with a single templated notice attached to your standard payment-terms communication. Expect roughly a third to be on the network already, a third to move when asked, and a third to need either a workaround or a conversation about whether you keep buying from them that way. Budget 90 days for the first two waves, and start with receiving rather than sending.

What does getting a supplier onto InvoiceNow actually mean?

It means two specific things, and conflating them is where most SME onboarding programmes stall.

First, the supplier must be registered on the Peppol network through an access point, with a Peppol ID that is discoverable in the directory. This is the part that makes them reachable. Second, their system must be able to issue a structured e-invoice to your Peppol ID, not just receive one. Plenty of companies complete the first step, quietly, as part of a software upgrade, and never switch on outbound invoicing. They are registered and still sending you PDFs.

Direction is independent. You can be fully capable of receiving while still sending PDFs, and so can they. That asymmetry is useful: the fastest wins in any supplier campaign are the counterparties who are already registered and simply need to flip outbound on, which is often a configuration change at their end rather than a project.

Why can't you just email every supplier and wait?

Because an undifferentiated email to 200 suppliers produces a response rate close to nothing, and the few replies you do get come from the suppliers who matter least. A supplier who sends you one invoice a quarter has no incentive to change anything for you. A supplier who sends you 60 delivery invoices a month has a very strong one, because they are also absorbing the cost of your staff keying those invoices in and chasing the mismatches.

There is also a sequencing problem. If you ask a supplier to move before you can reliably receive, you create an exception queue: structured invoices arriving into a system nobody is watching, while the PDF copy stops coming. Get your own receiving path working and monitored first, including who checks it daily and what happens when a document fails validation. Then start asking.

How do you segment your supplier list before you contact anyone?

Pull 12 months of accounts payable data and build four groups:

• Wave 1 — high volume, already registered. Cross-check your top 30 suppliers by invoice count against the SG Peppol Directory using their UEN. Anyone already registered is a phone call, not a campaign.
• Wave 2 — high volume, not registered. These are worth individual attention, including offering to walk their finance person through what you did. They are also the suppliers most likely to be caught by the GST InvoiceNow phases themselves, so you are telling them something they need to hear anyway.
• Wave 3 — low volume, GST-registered. Templated notice, attached to something they already read: a purchase order, a payment advice, your annual vendor declaration.
• Wave 4 — low volume, not GST-registered, or overseas. Leave them. They are under no obligation and the effort is not recoverable. Keep a PDF lane for them permanently.

If your supplier master data is too messy to produce that ranking — duplicate vendor records, UENs missing, the same company spelled three ways — fix that before you start writing emails. You cannot run a counterparty campaign off a list you do not trust.

What should the first supplier email actually say?

Short, dated, and specific. Four elements, in this order:

1. Your Peppol ID and legal entity name, so their finance team can register you as a customer without asking.
2. A target date for their first structured invoice to you — pick something 6 to 10 weeks out, not open-ended.
3. What stays the same: your payment terms, your PO process, your contact. Suppliers read e-invoicing requests as a precursor to a payment-terms squeeze. Remove that fear in one sentence.
4. A named person at your end with a direct line. Not accounts@. One human.

Do not include a technical explanation of Peppol four-corner routing. Their access point handles interoperability; a supplier on a different provider from yours can still invoice you, and saying more than that invites a two-week email thread about standards.

What do you do with the suppliers who refuse or can't comply?

Some will say no, and a few will be right to. A sole proprietor issuing you two invoices a year, a foreign vendor outside the network, a trade supplier whose system genuinely cannot emit a structured document — these are not compliance failures on your side. The GST InvoiceNow Requirement sits on GST-registered businesses in the phases IRAS has announced, and your obligations concern your own transmission to IRAS, not your supplier's choice of format.

What you need is a decision, written down, per supplier: move, keep on PDF with a named person responsible for keying it, or replace at next renewal. The failure mode is not refusal. It is an indefinite maybe, where somebody keeps re-sending the same email every few months and nobody ever decides the supplier is staying on paper.

For the genuinely large and genuinely immovable supplier, the practical middle path is a structured file drop or a supplier portal export that your access point or finance system can ingest. It is not InvoiceNow, it is not as good, and it is considerably better than a PDF in an inbox.

Which of your own records have to change at the same time?

Three, and they are usually forgotten until the first invoice bounces:

• Vendor master: a field for Peppol ID and a field for e-invoicing status, with a date. If this lives in a spreadsheet on someone's desktop, the campaign dies when they go on leave.
• Your purchase order template and vendor onboarding form: every new supplier from today forward should be asked for their Peppol ID at the point of onboarding. Otherwise you are adding to the backlog while clearing it.
• The exception process: who looks at failed or rejected documents, how often, and what the escalation is after 48 hours. This is the single most common gap in SME e-invoicing go-lives.

Confirm the current phase dates and your own obligations against the IRAS and IMDA published guidance before you commit to a timeline in writing to suppliers — the phased schedule for existing GST-registered businesses has been communicated in stages, and your access point should be able to tell you exactly which phase you fall into.

What does a realistic 90-day plan look like?

Days 1–14: clean the vendor master, pull the 12-month invoice count, check the directory, confirm your own receiving path works and is monitored daily.

Days 15–45: Wave 1 calls and Wave 2 emails. Target: your top 20 suppliers by volume all have a date or a written decision.

Days 46–75: first live structured invoices arriving from Wave 1 and early Wave 2. Run both the structured document and the PDF in parallel for two cycles per supplier, then stop the PDF deliberately rather than by accident.

Days 76–90: Wave 3 templated notice goes out with payment advices. Write the per-supplier decisions into the vendor master. Book a review for 90 days later with one number: percentage of purchase invoices arriving structured.

That number is the only metric worth reporting. Not how many suppliers were emailed — how much of your payables volume no longer needs a human to retype it.

FAQ

Do suppliers who are not GST-registered have to join InvoiceNow?
No. The GST InvoiceNow Requirement applies to GST-registered businesses in the phases IRAS has announced. A non-GST-registered supplier has no obligation to you or to IRAS, and you should plan on keeping a permanent PDF lane for that part of your supplier base rather than treating it as unfinished work.

Can we receive InvoiceNow invoices before we are ready to send them?
Yes, and for accounts-payable-heavy SMEs this is usually the better order. Receiving capability is what removes manual keying from your team's day; sending capability is what satisfies the GST transmission requirement when your phase arrives. They are separate switches and can be scheduled separately, as long as you know your own phase date.

What if a supplier uses a different access point from ours?
It does not matter. Peppol is a four-corner model: their access point and yours interoperate, in the same way two banks exchange a transfer without being the same bank. You do not need to match providers with any counterparty, and no supplier should be told they must switch to yours.