What the control unit is and what it stamps
Every compliant tax receipt in Kenya is signed by a control unit before it reaches the customer. The control unit is the trusted component in the chain: it receives the invoice from the seller’s system, applies a signature that cannot be forged, assigns the invoice a reference, and transmits the record to KRA. Everything printed on a compliant receipt that a buyer can verify comes from that moment.
Two numbers come out of it and they are frequently confused. The CU invoice number is the reference for that specific invoice, unique within the device that issued it. The CU serial number identifies the device itself. One says which sale; the other says which machine. A verification generally needs both, which is why both are printed.
Alongside them a compliant receipt carries a QR code. The QR code is not decoration and it is not a link to the shop. Scanning it takes you to KRA’s verification for that specific invoice, which is the fastest possible way to check a receipt: point a phone at it and read the answer. Most people holding a receipt and searching for a checker do not realise the checker is already printed on the paper in their hand.
The reason this architecture exists is worth understanding, because it explains what a failed check means. The signature and transmission happen together. There is no compliant path by which an invoice gets a valid CU number without KRA receiving the record. So a receipt whose CU details do not verify is not a receipt with a clerical error. It is a receipt for a sale that was not declared.
Older ETR and TIMS receipts and newer eTIMS invoices differ in the detail of what is printed and how, but the principle has been constant: a compliant receipt carries a device-issued reference that a third party can check independently of the seller. That independence is the entire value of the system.
It is worth being precise about what a successful check does and does not prove, because the distinction decides what you do next. A verification that returns the invoice proves the seller declared a sale with those references, on that date, for that amount, under that PIN. It does not prove the goods were delivered, the price was fair, or the supplier is solvent. It is a tax fact, not a commercial one. What makes it valuable is narrow and real: it is the one thing about a supplier you can confirm without taking their word for anything.
The other thing worth knowing is who tends to check. In practice it is finance teams processing invoices for payment, businesses claiming input VAT, and occasionally a customer who has been given a receipt that looks wrong. The checking is increasingly routine among larger buyers, which means a supplier whose invoices do not verify will eventually be found out by a customer rather than by KRA -- and that is a commercial problem before it is a tax one.
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Sign UpThe checker you are looking for is usually printed on the receipt already. It is the QR code.
How to verify an invoice
Fastest route first. The later steps cover what to do when the quick check does not resolve it.
- 1
Scan the QR code on the receipt
Open your phone camera, point it at the code, and follow the link. It takes you to KRA’s verification for that exact invoice, with no numbers to type and no chance of a transposition error. If a receipt has a QR code, this is always the right first move.
- 2
Find the CU numbers if there is no code to scan
Look for a line labelled with the control unit invoice number and another with the control unit serial number. They sit near the bottom of the receipt on most layouts, close to the KRA PIN. On an A4 tax invoice they are usually in the footer block rather than beside the totals.
- 3
Use the KRA invoice checker
KRA provides an invoice verification page on its own site. Enter the details it asks for exactly as printed. Reach it through KRA’s official website rather than through a search result or a link somebody sent you, for the same reason you would not enter your PIN on a page you reached from a text message.
- 4
Compare what comes back with what you are holding
A successful check returns the invoice as the seller declared it. Compare the supplier PIN, the date, the total and the VAT against the paper in your hand. A verification that succeeds but shows a different amount is a more serious finding than one that fails, and it is the one people skim past.
- 5
Retype carefully before concluding anything
Before treating a failure as fraud, re-enter the numbers. A confused 0 and O, or a missing character on a faded thermal print, accounts for a good share of failed checks. Two careful attempts is the right threshold.
- 6
Allow for a short delay on very recent invoices
An invoice issued minutes ago on a connection that has just come back may not be queryable yet. If the sale was very recent, wait and check again before escalating. A day-old invoice that still does not verify is a different matter.
- 7
Ask the supplier, specifically
If it still fails, go back to the supplier with the invoice number and ask them to confirm it was transmitted. An honest seller with a technical problem will be able to tell you what happened and reissue. A seller who becomes evasive at this question has answered it.
- 8
Do not claim input VAT on an invoice that will not verify
If you are VAT-registered, an unverifiable invoice is not support for a claim. Claiming on it puts the exposure on you, not on the supplier who issued it. Hold the claim until the invoice verifies or is reissued.
- 9
If you are the seller, check your own output regularly
Do not wait for a customer to discover a problem. Pick a few invoices a week at random and verify them the way a buyer would. It takes a minute and it catches a transmission failure while it is still one day of invoices rather than a month.
What people get wrong about the check
Assuming a printed KRA PIN means the receipt is compliant
Anybody can print a PIN on a document. Only a control unit can produce a valid CU invoice number that KRA recognises. The PIN is not the verification; the CU details are.
Confusing the CU serial number with the invoice number
The serial identifies the device and will be the same on every receipt from that machine. The invoice number changes with each sale. Entering one where the other belongs fails the check for no real reason.
Reaching the checker through a search result
Verification pages are an obvious target for lookalike sites. Navigate to KRA’s own domain yourself, or scan the QR code on the receipt, which goes where it is supposed to go.
Treating a successful check as the end of it
Verification proves an invoice with those references exists and was declared. It does not prove the amounts match your copy. Compare the figures too, particularly on larger purchases.
Accepting a handwritten or reprinted substitute
A supplier who cannot produce a verifiable invoice and offers a handwritten one instead is offering you a document with no tax standing. Politely decline and ask for a proper reissue.
A supplier invoice that did not check out
An office manager in Westlands receives an invoice for KES 180,000 of equipment from a new supplier, with VAT stated on it. Before passing it for payment she scans the QR code. Nothing comes back.
She retypes the CU numbers by hand into KRA’s checker in case the print was poor. Still nothing. The invoice is two weeks old, so a transmission delay is not a plausible explanation. She calls the supplier, quotes the invoice number, and asks them to confirm it was transmitted. The supplier promises to check and sends a fresh copy the next day with different CU details, which verify correctly.
It cost her four minutes and it protected an input VAT claim of nearly KES 25,000 that she would otherwise have made on a document with nothing behind it. The lesson her finance team took from it was not that the supplier was dishonest. It was that verifying before paying is cheap, and unwinding a disallowed claim is not.
Trading without eTIMS-compliant tax invoices risks KRA penalties, blocked VAT input claims for your customers, and receipts a business buyer cannot expense.
Veira signs every sale to KRA eTIMS automatically, so each receipt is compliant the moment it prints, with no separate device to reconcile.
Invoices that verify every time
Veira issues invoices through eTIMS, so every receipt your customers receive carries proper CU details and a working QR code. A buyer who checks gets the answer they expect, which is quietly one of the most useful things a supplier can offer a business customer.
If the connection drops mid-trading, invoices queue and transmit when it returns rather than being issued without a signature. You are never handing a customer a document that will fail a check later.
Your own transmission status is visible rather than assumed, so a problem surfaces as an alert on your side instead of as a phone call from a customer who could not verify a receipt.
Frequently asked questions
What does CU mean on a Kenyan receipt?
What is the difference between the CU invoice number and the CU serial number?
Where do I find the KRA invoice checker?
What does it mean if an invoice does not verify?
Can I claim VAT on an invoice that will not verify?
Why do some receipts have no CU details at all?
Does the QR code do the same thing as the checker?
How soon after a sale can an invoice be verified?
I am the seller and my invoices do not verify. What now?
What does a successful verification actually prove?
Who usually checks invoices?
Should buyers really check every invoice?
The CU numbers on a Kenyan receipt exist so that nobody has to take a seller’s word for it, and checking them is the fastest piece of due diligence available to a business. Scan the QR code, compare the figures, and hold any claim on an invoice that does not come back clean. If you are on the selling side, verify a handful of your own invoices each week: it is the difference between finding a transmission fault on day one and finding it in a customer’s complaint a month later.
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