Duplicate payments in the accounts payable ledger: how they happen and how to find them afterwards

A duplicate payment is when the same supplier debt is paid more than once. It can be the same invoice paid twice. It can also be the same cost arriving on two different invoices. The money then stays with the supplier until someone discovers the error and asks for it back.

Duplicate payments occur in municipalities, regions and private companies. They are seldom caused by carelessness. They often arise where several routines meet, for example with payment reminders, system changes or changed supplier details.

How do duplicate payments arise?

Here are some common patterns. They are general and are not based on any single client.

• The reminder is paid too. The invoice is paid on time. A reminder arrives anyway, perhaps because the payment and the reminder crossed. The reminder is registered as a new invoice and is paid.
• The same invoice through different channels. The invoice arrives as an e-invoice and as a PDF by email. Or as paper that is scanned. It is registered once per channel.
• A new bank giro number or a new payee. The supplier changes bank giro number or starts invoicing through a finance company. The supplier is set up once more in the register. The same debt can then be paid to both the old and the new payee.
• The credit note is not offset. The supplier sends a credit note and a new, corrected invoice. The new invoice is paid. The credit note is left lying and is never offset.
• Small differences in the invoice number. A zero in front of the number, a space or an extra character. The system sees two different invoices.
• System change. When the finance system or scanning service is changed, invoices can be transferred and then registered again.

Why does the finance system not catch them?

Most finance systems have a duplicate check. It often looks for the same supplier, the same invoice number and the same amount. This works well for exact duplicates.

The problem is the variants. If the supplier is in the register twice, the system sees two suppliers. If the invoice number differs by one character, the system sees two invoices. If the amount differs by a few SEK, for example because of a fee, the entry can also pass.

Approval does not help in every case either. The person approving sees one invoice at a time. It is hard to see that the same cost was paid three months ago.

How do you find duplicate payments afterwards?

The basic idea is simple. You take the whole accounts payable ledger for several years. Then you compare the entries with each other, not just against one rule at a time.

A review can for example look at:

• invoices with the same amount and nearby dates at the same or similar suppliers
• invoice numbers that are almost the same
• suppliers with the same corporate identity number but several entries in the register
• bank giro numbers and account numbers that have been changed, and payments before and after the change
• credit notes that have not been offset against any payment
• reminders and demand letters that have been registered as invoices.

Each hit is only a suspicion to begin with. It must be checked against the invoice itself, the payment and the supplier’s statement of account. Only then do you know whether it is a duplicate payment or two genuine purchases. That is the step that takes time.

What can you check yourselves?

Some simple checks can often be done in your own system:

1. Search for suppliers that appear more than once with the same corporate identity number.
2. Take out all credit notes for one year and see whether they have been offset.
3. Sort invoices by amount. Is the same amount found at the same supplier within a short time?
4. Look at how reminders are handled. Are they registered as new invoices?
5. Ask your largest suppliers for a statement of account balance. A credit balance with the supplier can be a sign.

This gives a picture, but not the whole picture. A review of several years, entry by entry, takes more time than most finance functions have in everyday work.

Can the money be recovered?

In many cases it can. A duplicate payment is normally a claim against the supplier. It is therefore not a tax matter. Under the Swedish Limitation Act (preskriptionslagen) a claim is, as a main rule, time-barred ten years after it arose, unless the limitation period is interrupted. Contracts and circumstances can affect this.

The possibility can also be affected by the supplier’s finances. If the supplier has gone bankrupt, it can be hard to recover the money. It can therefore be a good idea not to wait too long.

The time limits for VAT and VAT compensation are shorter and work differently. Read more in our Swedish article on the deadlines on 31 December 2026.

How Refero works with the accounts payable ledger

The review is part of our VAT and transaction analysis. We go through the whole material for the years included, not only samples. Each discrepancy is verified against the records before it is reported.

In about 99% of assignments we are given read-only access and extract the records ourselves. The time required from you is normally 2 to 5 hours, spread over 1 to 3 months. We have three check-in meetings with you during the work. We do not use AI or machine learning in our analysis work.

Our fee is often a share of the amount recovered. It is set out before work begins. There is no charge for the first conversation.

We do not promise how much we will find. How much a review yields depends on your own records.

Read more

• Recovery audit in Sweden: what the Swedish terms mean
• Three years of supplier payments in a Swedish municipality
• Procuring a financial review, with a section on direct award
• Facts about Refero

The text is general information, not legal advice.