Supplier Onboarding: Which Documents to Collect and What to Verify in Each

This is an operational description of what is collected and how it is verified, not tax or legal advice. What must be retained and for how long, and which withholding rate applies, is settled with the accountant. What is purely operational: an orderly supplier onboarding takes ten minutes and prevents most of what gets stuck later on payment day.

The list

The Tax Authority allows checking withholding and bookkeeping certificates by business, company or ID number. It is the cheapest check on the list, and also the most annoying one to have skipped - because it surfaces on the day the payment is due to leave.

Why bank details are a special case

Every other item on the list is verified against a document or a system. Bank account details are the only one verified against a person, and on a different channel from the one they arrived on.

The reason is that this is the precise vector of supplier-change fraud: an email that looks right, at the right time, with a reasonable request. Verification by a call to a number already stored in your system - not the number in the email - is all it takes, and it should be a built-in action at onboarding and at every change. The same rule recurs in a weekly supplier payment run, for the same reason.

The item everybody forgets: where the invoice is sent

It looks like an administrative detail and it is a leading source of missing documents at period close. A supplier sending to the personal address of whoever ordered, or attaching the invoice to the delivery, produces a document that will arrive - if at all - after the period closed.

So supplier onboarding should include an explicit request: invoices go to one business address, not to a person. That takes one sentence on the onboarding form and eliminates a whole category of gaps, as described in the VAT period routine.

Three supplier categories that need different lists

Not every supplier justifies the same list, and insisting on a uniform one is what makes people bypass it:

• An ongoing supplier - the full list, because there will be dozens of payments.
• A one-off supplier for a small amount - entity details and verified bank details; the rest from what can be checked online.
• A subcontractor working in front of your customers - the full list plus: who owns them on your side, and what they may say on your behalf.

The third tends not to be seen as a supplier list at all, and it carries the higher risk - because what the subcontractor does in front of the customer is attributed to your business. That is not a documents matter but a definition matter, and it belongs at onboarding rather than to a conversation after an incident.

When to recheck

1. Start of the year - certificates renew, making this a natural checkpoint.
2. Before the first payment of the year to each supplier - instead of checking everybody at once.
3. On any notice of changed details - verification on a separate channel, always.
4. When a supplier returns after a long gap - details go stale even when nobody changed them.

The second option is better at most small businesses: it spreads the work, checks only active suppliers, and fits at the point where you already stop to check documents.

Where this is kept

The list is only worth something if its answers live in one place whoever pays can open in a second. In practice, at most small businesses the information is scattered: the entity in the agreement, the bank details in an email, the certificates in a folder, and the payment terms in the memory of whoever closed the deal.

What is needed is not a system but one supplier record - a spreadsheet row or a card in whatever you run - holding the six items and the date each was last checked. The date is what lets you know what is current without opening anything.

The check that reveals whether this exists is simple: pick a supplier at random and try to answer within a minute what their withholding rate is and when it was checked. If you have to search, the list exists and is not being applied.

What to do with a supplier who will not provide a document

It happens, usually with very small or one-off suppliers. The operational answer is neither to give up nor to get stuck, but to define in advance what blocks and what does not.

The rule that works: a document that can be checked online does not depend on the supplier at all, so its absence is not a blocker - you check and record the result. Unverified bank details are an absolute blocker, because a payment to an unverified account cannot be recalled. And an invoices address does not block payment but is an item to return to, because it will generate work later.

How long does it really take?

Fully onboarding a new supplier, with the list in place and somebody owning it, is ten to fifteen minutes. The same onboarding done in retrospect - on the day the payment is due, with the supplier waiting - is at least an hour, and usually spreads over two days because of the calls back and forth.

That is the whole argument: this is not extra work but the same work, at the moment it is cheap. What decides is whether it happens before the first invoice or after it.

Sources

• Israel Tax Authority - withholding and bookkeeping certificates
• Checking a withholding tax certificate before paying a supplier
• A weekly supplier payment run
• Book a call