Duplicate invoices
How do I find duplicate invoices before I pay them, for free?
Last updated
There are three free ways, from manual to automatic: list your bills in Excel and flag any supplier and invoice number that appears twice; switch on your accounting system’s own warning (QuickBooks Online can warn when a bill number is reused for the same vendor); or use InvoiceParser Pro’s free plan, which checks every invoice you upload against the past year of invoices in your workspace, for 25 invoices a month at no cost. A large AP team paying thousands of invoices a month from an ERP will want a dedicated duplicate-payment tool instead; our comparison of math and duplicate checkers lists them.
Without IPP
Check for duplicates in Excel
- 1
List the bills
Export your unpaid and recent bills, or type the new batch, with one row per invoice: supplier in column A, invoice number in B, date in C, total in D.
- 2
Count supplier and number together
In E2 enter =COUNTIFS(A:A,A2,B:B,B2) and fill it down. Any row showing 2 or more has the same supplier and invoice number as another row.
- 3
Highlight exact repeats
In F2 enter =A2&"|"&B2, fill it down, select column F and choose Home, Conditional Formatting, Highlight Cells Rules, Duplicate Values.
- 4
Look for near-duplicates
Sort by supplier, then total, then date. The same total from the same supplier a few days apart, or invoice numbers that differ only by a dash or a leading zero (INV-1001 and INV1001), deserve a second look.
- 5
Check before you pay
Compare each suspect pair with the paper. A re-sent copy, a statement entered as an invoice, or the same bill entered under two spellings of the supplier are the usual causes.
Checked against Microsoft: COUNTIFS function and Microsoft: Find and remove duplicates, read 4 October 2026. Menus change; the vendor's page is the authority.
Without IPP
Turn on QuickBooks Online’s duplicate bill number warning
- 1
Open the settings
Select the gear icon, then Account and settings, then Advanced.
- 2
Turn the warning on
Under Other preferences, turn on the option to warn when a bill number has already been used for that vendor, then Save and Done.
- 3
Enter bills as usual
QuickBooks now warns when you type a bill number already used for the same vendor.
- It compares the bill number for the same vendor only. A bill entered under a second spelling of the supplier, or a number typed slightly differently, gets no warning.
Checked against QuickBooks community: duplicate bill number warning, read 4 October 2026. Menus change; the vendor's page is the authority.
In InvoiceParser Pro
Let InvoiceParser Pro check every upload
- 1
Open a free workspace
Sign up with no card. The free plan reads 25 invoices a month, and every one is checked for duplicates. A new workspace starts on a 14-day trial with 50.
- 2
Upload or forward invoices
Each new invoice is compared with the past year of invoices in the workspace: the same supplier, number, total and date; the supplier’s name written a little differently; and similar amounts on nearby dates. Statements are not treated as invoices.
- 3
See why it matched
A possible duplicate is flagged with the invoice it matched and the reason. Invoices that state different invoice numbers are never grouped as duplicates, so a batch of real bills with sequential numbers is not flagged as one.
- 4
Decide which copies to keep
In the Duplicates tab, tick the copies to keep. Removed copies go to Trash for 30 days; “Not a duplicate” is remembered and the pair does not come back. Nothing is ever deleted automatically.
- A possible duplicate is held out of auto-approve when you switch it on, and pushing one to QuickBooks, Xero or Zoho Books (paid plans) asks you to confirm first.
Where duplicate invoices come from
Most duplicates are not fraud. They are the same bill arriving twice:
- emailed and then posted, or sent again as a reminder with “copy” stamped on it;
- a supplier statement entered as if it were an invoice;
- the same invoice entered under two spellings of a supplier name;
- a scan of a scan, uploaded by two people in the same team.
What IPP does not do
- It checks invoices in your workspace, not payments in your bank or bills keyed straight into your accounting system.
- The free no-signup tool on /invoice-to-excel keeps no history, so it cannot check for duplicates; a workspace can.
- The free plan is one user and 25 invoices a month, and the push to QuickBooks, Xero or Zoho Books is on paid plans and the trial.
- It flags and asks; it never removes an invoice on its own.
Questions
Is there a free duplicate invoice checker?
Yes. InvoiceParser Pro’s free plan checks every invoice you upload against the past year of invoices in your workspace, for 25 invoices a month with no card. Excel and QuickBooks Online’s duplicate bill number warning are free too, with the limits described above.
How do I find duplicate invoices in Excel?
Put supplier and invoice number in two columns and use =COUNTIFS(A:A,A2,B:B,B2); a result of 2 or more is a repeat. Then sort by supplier, total and date to spot near-duplicates the formula misses.
Will two different invoices with the same amount be flagged?
They may be flagged as possible duplicates if they come from the same supplier on nearby dates, with the reason shown. If they state different invoice numbers, IPP never groups them as duplicates, and “Not a duplicate” is remembered.
Does QuickBooks Online warn about duplicate bills?
It has a setting under Account and settings, Advanced, to warn when a bill number is reused for the same vendor. It does not catch a different spelling of the supplier or a slightly different number.
What happens to a duplicate I remove in IPP?
It goes to Trash for 30 days, then it and its file are permanently deleted. Until then it can be restored.
Try it on one of your own invoices
Upload a PDF or a phone photo on the free tool, with no account (up to 3 invoices a day), and download the result as Excel or CSV. When you want more: the free plan reads 25 invoices a month; the 14-day trial gives you 50 invoices and the QuickBooks, Xero and Zoho Books push, with no card.