How to find duplicate invoices in Excel

Highlight repeated invoice numbers with conditional formatting, then use a COUNTIFS formula to flag rows where the same vendor and invoice number appear more than once. Remove Duplicates also works, but it deletes rows, so use it on a copy.

Why duplicate invoices happen

A supplier resends an invoice, or a statement repeats it.
It is entered once from email and once from paper.
Numbers are formatted differently, such as INV-001 and 001.

Steps

Assume vendor in column A, invoice number in column B, and data in rows 2 to 500.

Work on a copy of the file.
Highlight: select the invoice number column, then Home, Conditional Formatting, Highlight Cells Rules, Duplicate Values. Choose a style and OK. This flags numbers that repeat across all vendors, so two vendors that both use 1001 will both light up.
Flag by vendor and number: in C2 enter =COUNTIFS($A$2:$A$500,A2,$B$2:$B$500,B2) and fill down. COUNTIFS counts rows where every condition matches, so any value above 1 is a candidate.
Filter column C for values above 1 and read those rows side by side.
Optional: Data, Remove Duplicates, and tick only the columns you want compared. Microsoft says removed rows are permanently deleted, so only do this on a backup copy.

Limits of the manual method

Matching is exact. INV-0042 and 42 are different, and so are values with a trailing space.
The same amount a week apart under a new number is not caught.
Remove Duplicates can delete a legitimate repeat, such as a monthly charge.
Reported counts after removal may include empty cells.

FAQ

Is highlighting or COUNTIFS better?

COUNTIFS, because it checks vendor and number together and you can filter on the result.

How do I handle numbers formatted differently?

Add a helper column that cleans the number, for example by removing prefixes, then run the checks on that column.

How do I save my sheet as CSV for Catchfold?

Use File, Save As, and choose CSV. Only the active sheet is saved and formatting is dropped.

Check it automatically with Catchfold

Catchfold is a free tool that runs in your browser. Export your bills as a CSV, open Your files, and pick the file. It never leaves your computer. Catchfold flags bills that look like possible duplicates, or whose totals do not add up, and a person decides what to do. It never pays, blocks or approves anything. It is a free prototype with no guarantee, and it will not catch every duplicate. The pilot guide has export steps for other tools.

Related guides

Sources

Menus change; the vendor's help page is the source of truth.

Checked against vendor pages on 23 October 2026.