How to Check an Invoice Before You Pay It
Once you pay a bill, the money is hard to get back. Before you pay, it is easy to hold. That is why the check lives at this gate. This guide shows how to verify an invoice in five checks. They take a few minutes, and they catch the wrong bills, the twin bills, and the fake ones.
Work from the bill's own sheet when you can. A bill in a sheet is faster to check than a bill in a PDF: sums add themselves, and twins sort to the top. Our invoice to Excel converter gives you that sheet, with the math checks built in. The five checks below are the rest — the parts that need your eyes and your knowledge of your own firm.
None of the five needs a finance degree. Each one asks a plain question in plain words: do we know this firm, did we get this stuff, do the sums hold, have we paid this before, is this the deal we made? If you can ask those five, you can run this gate. What follows is how to ask each one well.
Check one: the vendor is who you know
Start with the name. Is this a firm you buy from? Does the name match the one on your past bills, letter for letter? Fake bills lean on near-miss names and fresh logos. A bill from a firm you have never used is not a bill to pay fast — it is a bill to ask about. Check the bank facts too. If a known vendor's bank name or account has changed with no word from them, call the number you have on file — not the one on the bill — and ask.
This check takes a minute and stops the boldest fraud there is: a bill from no one, for nothing, paid by a busy hand. Your vendor list is the wall. A name not on the list does not get paid till a person says why it should be.
New vendors are fine — firms change suppliers all the time. The rule is not “never pay a new name”. The rule is “a new name gets set up first, by a person, with the firm's real facts on file: name, tax form, bank, and a phone number you found on your own”. Set up once, then the bills flow. A bill that asks you to skip the set-up and just pay is telling on itself.
Some bills fail this check at a glance. Learn the flags:
| Red flag | Why it counts |
|---|---|
| The bill wants pay by gift card or wire to a new name | Real vendors bill through real banks |
| Hard rush: “pay today or else” | Rush is how fakes skip your checks |
| The name is one letter off a known vendor | Near-miss names are made to slip past eyes |
| No bill number, or a round, made-up one | Real billing systems print real numbers |
| The contact facts differ from your file | The bill may not be from who it claims |
One flag is a question. Two flags are a hold. The bill waits while you call the firm on a number you trust and ask, in plain words, if the bill is theirs. That call takes three minutes and ends most fraud at the gate.
Check two: you got what the bill lists
Match the bill to what came in. The rows on the bill should be the goods on the shelf or the work that got done. If you use order forms, match the bill to the order and to the delivery note: three papers that should tell one tale. Counts first — did ten come, or eight? Then kinds — is this the part you asked for, or the dearer one?
Rows are where this check lives or dies. A total can look right while the rows hide a swap. To read rows well — what a clean row looks like, and how to spot one that is off — see our guide on how to get line items out of an invoice PDF. If row counts and shelf counts fight, hold the bill and ask the person who signed for the goods. Their note settles most fights in a day.
For work, not goods, the “delivery” is proof the work got done: a signed sheet, a job card marked done, a photo of the fixed thing. Ask for that proof as a habit, not as a slight. Good vendors send it with the bill once they know you look. Vendors who balk at proof are telling you a thing about the bill.
Check three: the math holds
Now the sums. Add the rows: they should give the subtotal. Add tax: it should give the total. Spot-check two rows: count times price should give the row sum. If a sum fails, the bill waits. A vendor slip is common and no crime — but you pay the fixed bill, not the flawed one.
Pick the two rows to spot-check with care: the biggest row, and one at random. The biggest holds the money risk. The random one keeps the check honest — a check that only looks where it expects trouble will miss the trouble it does not expect.
Gaps have known causes — a missed fee line, tax counted twice, a digit read wrong. Our guide on why invoice totals don't add up walks through them and shows how the size of a gap points at its cause. Run the math check there the same way you run it here: first the row sum, then the tax sum, then the odd row.
| Check | What you look at | A pass looks like |
|---|---|---|
| Vendor | Name and bank facts vs your list | Same name, same bank as last time |
| Goods | Rows vs what came in | Counts and kinds match |
| Math | Row sum, tax sum, two rows by hand | Each sum ties out |
| Copy check | Bill number vs paid list | No match — it is new |
| Terms | Due date and price vs your deal | Same terms as agreed |
Check four: you have not paid it before
Twin bills are the most common way good firms pay twice. The same bill can come by email and by post. A vendor can resend a bill you asked about, with a fresh date. A bill can be keyed in twice from two desks. Each path ends the same: two pays for one debt.
The check is a match on three facts: vendor, bill number, and total. If all three match a bill you have paid, stop. If the number is new but the sum and date match an old bill, look twice — some vendors renumber a resend. A sheet makes this check fast: sort by vendor and sum, and twins sit side by side. Make the match a step in the pay run, not a thing you do when you “have time”. Twins do not wait for you to have time.
Watch the near-twin too: same vendor, same goods, a sum a few cents off the last one. That can be a resend with a fee added, or a real second buy that just looks like the first. The rows tell you which: if the rows are the same goods on the same dates, it is one buy billed twice. If the dates differ, it is a fresh bill that earns its own pay.
Check five: the terms match your deal
Last, the deal itself. Is the price the price you agreed? Check unit prices on the big rows against your last bill or your quote. Prices creep: a small rise on each bill, none of them flagged, adds up to real money by year's end. Is the due date the one in your terms? A bill that wants pay in seven days when your deal says thirty is a bill to query, not to rush.
Terms also guard your cash. Pay too soon and your bank feels it; pay late by slip and fees land. The due date on the bill, checked against your deal, sets the pay day. Put the bill in the pay run for that day — not the day it lands on your desk, and not the day the vendor calls.
Keep the proof of the deal where the checker can reach it: the quote, the price list, the terms on the order. A terms check with no deal to check against is a guess. With the quote in hand, it takes a glance: same prices, same terms, pass. Price checks feel slow the first week. Then they turn into the fastest of the five, since most bills match the deal at a glance.
When a check fails: hold, ask, note
A failed check is not a fight. Hold the bill, ask a short, clear question, and note what you asked. Most fails end as dull slips: the vendor sends a fixed bill, or shows you the line you missed, and you pay with a calm mind. The note matters: write the cause on the bill's record in one line. If the same vendor fails the same check next month, your notes show a pattern — and a pattern is a talk worth having.
One word on scans. If the bill came as a scan, a blurred digit can make a good bill look bad — the math fails on a sum the page never held. Before you query the vendor, check the scan's weak spots: the total and the rows. Our guide on how to turn a scanned invoice PDF into Excel shows what scans read well and what to re-check by eye.
And if the vendor can not explain a fail — or the bill is from a firm no one knows — do not pay. A real vendor can always show their work. The hold costs you a phone call. The pay can cost you the sum, for good.
For big bills, add a second checker. Set a line — any bill over a sum you pick — where a second person runs the five checks fresh, not off the first person's notes. Two readers catch what one tired reader waves through, and the mere fact of the rule slows down any fake that counts on haste. Small firms can swap the role week by week. The point is the second pair of eyes, not the size of the team.
Your next step
Make a one-page list of the five checks and keep it where bills get paid. Run it on the next bill that lands, start to end. It will take five minutes the first time and two once it is a habit. More on checks, scans, and edge cases lives in our FAQ.
The habit pays for itself the first time it stops a twin or a fake. After that, it is just how bills get paid at your firm — checked, noted, and right.
Print the list. Tape it by the screen where bills get paid. New hands learn the gate by watching it run, and the list keeps the gate the same when you are out. Five checks, one page, zero guesswork: that is the whole system, and it fits on an index card.
Sources and further reading
- Topic no. 305, Recordkeeping — The IRS on keeping the records that back up each sum — the proof your checks rest on.
- Manage your business — The US Small Business Administration's guide, fraud protection and sound bookkeeping included, for firms that pay bills each week.