eTIMS

eTIMS Signature Error: Why an Invoice Will Not Sign

K By Kev 14 June 2026 7 min read
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eTIMS guide

eTIMS signature error is frustrating when you are mid-sale and a customer is waiting, but it is almost always fixable in a few minutes. It means the control unit could not apply its digital signature to the invoice. This guide explains why it happens, how to fix it step by step, and how to stop it from happening again, in plain language for a Kenyan business.

Quick answer

An eTIMS signature or control unit error means the invoice could not be signed by the control unit, usually because the control unit is offline, not registered, or the device clock is wrong. Confirm the control unit is connected and registered, fix the device date and time, and resubmit.

Key takeaways
  • eTIMS signature error usually has a small number of specific causes, each with a clear fix
  • Work through the causes in order; most are resolved in a few minutes without calling KRA
  • Recording sales offline and syncing later prevents the most common transmission-related failures
  • A POS that handles eTIMS natively, like Veira, avoids most of these errors at the source
On this page
  1. Why eTIMS signature error happens
  2. How to fix eTIMS signature error
  3. What not to do
  4. A worked example
  5. How Veira keeps this from happening
  6. Frequently asked questions

Why eTIMS signature error happens

eTIMS signature error is not random. It comes from one of a few specific causes, and once you know which one you are looking at, the fix is straightforward. Here is how the problem usually shows up first:

- An invoice will not get a control number or QR code

- A signature or control unit error on submission

- It affects every invoice until resolved

Match what you are seeing to the closest description above, then work through the fixes below in order, starting with the most common.

eTIMS signature error is rarely random; match the symptom to the cause and the fix is usually minutes away.

How to fix eTIMS signature error

Work through these in order. Most businesses resolve it at step one or two, without contacting KRA.

  1. 1

    Confirm the control unit is connected

    The control unit (OSCU or VSCU) signs the invoice. If it is offline, nothing can be signed. Confirm it is connected and online, then resubmit.

  2. 2

    Check the control unit is registered

    An unregistered device or control unit cannot sign. Confirm the unit was onboarded to your account; if not, complete the registration.

  3. 3

    Fix the device date and time

    A wrong device clock breaks signing, because the timestamp must be valid. Set the device to automatic date and time and the correct time zone, then try again.

  4. 4

    Restart and resubmit

    If the connection, registration and clock are all correct, restart the control unit or app and resubmit the invoice. A restart clears many temporary signing faults.

What not to do

Do not hand over an unsigned invoice

An invoice without a control unit signature is not compliant. Resolve the signing first, then issue.

Do not keep resubmitting without changing anything

If the cause is the connection, registration or clock, fix that first; resubmitting alone will keep failing.

A worked example

Worked example

A till started throwing a signature error on every sale one morning, and nothing would print a control number.

The device clock had drifted to the wrong time after a battery issue, which broke signing. Setting the date and time to automatic fixed it, and invoices signed normally again.

A signature error usually comes down to the control unit being offline or unregistered, or a wrong clock. Check those three and it resolves.

Business impact

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.

How Veira keeps this from happening

Veira handles eTIMS natively at the point of sale, so the conditions that cause eTIMS signature error are managed for you. It validates the invoice before it is sent, records sales offline when the network drops and transmits them to KRA when the connection returns, and keeps your KRA details in order so the common causes never arise.

When something does need attention, Veira flags it in plain language with the next step, and local support is on hand rather than a queue. See how Veira works and book a free demo. It runs from KES 2,999 a month with a free terminal.

Frequently asked questions

What is an eTIMS signature error?
It means the control unit could not sign the invoice, so it gets no control number or QR code. The usual causes are the control unit being offline or unregistered, or the device clock being wrong. Fix the cause and resubmit.
Why does eTIMS fail to sign my invoice?
Because the control unit (OSCU or VSCU) cannot apply its signature, usually because it is offline, not registered to your account, or the device date and time are wrong. Confirm each of those and try again.
How does the device clock affect signing?
The signature includes a valid timestamp, so a device clock set to the wrong time breaks signing. Set the device to automatic date and time and the correct East Africa time zone, then resubmit the invoice.
Is an unsigned invoice valid?
No. A compliant eTIMS invoice must be signed by the control unit and carry a control number and QR code. An unsigned invoice is not valid, so resolve the signing error before handing it to the customer.
What should I do if signing keeps failing?
Confirm the control unit is connected and registered and the clock is correct, then restart the unit or app and resubmit. If it persists, your integrator or supplier can check the control unit configuration.

eTIMS signature error is almost always one of a few known causes, each with a quick fix, so do not panic if you hit it during a sale. Work through the steps above, and if you would rather not deal with eTIMS errors at all, Veira handles compliance natively so most never happen. See how Veira works and book a free demo. Always confirm current KRA processes at kra.go.ke, as rules can change.

For more eTIMS guides and compliance resources, visit our free resource site.

Terms explained

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