What a control unit does
Every compliant eTIMS invoice is signed by a control unit, which applies the digital signature and control number and transmits the invoice to KRA. Without it, an invoice is not compliant.
eTIMS offers more than one type of control unit so that a single phone till and a large integrated system can both comply. The two you will hear about are the OSCU and the VSCU.
The distinction is about where the control unit lives and how it reaches KRA, and the practical consequences show up in failure rather than in normal trading. When everything works, the two look much the same from behind the counter. When something breaks, they break differently and are diagnosed differently, which is why knowing which you run is worth more than the abstract comparison.
Choose from how the business actually operates rather than from a feature table: where invoices are raised, how many devices must issue them, and how dependable the connection is at that point. A setup that suits a single fixed till is not automatically the one for five counters or for a business that sells away from its premises.
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Sign UpHow to choose between OSCU and VSCU
- 1
Consider your invoice volume
A virtual control unit often suits higher volumes and integrated systems; a device-tied online unit can suit simpler, single-point setups. Match the unit to how much you invoice.
- 2
Consider how you issue invoices
If you use an integrated POS or ERP, a VSCU usually fits the integration. A simpler standalone setup may use an OSCU.
- 3
Check your integrator or POS support
Your POS or integrator will usually recommend and set up the control unit that fits their solution. Confirm what they support.
- 4
Confirm with KRA
Requirements and the available options change. The choice should follow from where invoices are raised, how many devices issue them, and how dependable the connection is at that point.
- 5
Establish which one you are running
Before any troubleshooting, know which model you have. The same symptom has different causes and different fixes under each.
- 6
Confirm current requirements with KRA
Setup requirements for both are KRA’s to define and are revised. For a new site, decide from how that site actually trades rather than copying the configuration of an existing one.
OSCU vs VSCU at a glance
| OSCU | VSCU | |
|---|---|---|
| What it is | Online sales control unit, device-tied | Virtual sales control unit, software-based |
| Typical fit | Simpler or single-point setups | Integrated systems and higher volumes |
| Signs invoices for KRA | Yes | Yes |
| Produces a compliant invoice | Yes | Yes |
| Set up by | You or your integrator | Usually your integrator or POS |
Mistakes to avoid
Assuming one is more compliant than the other
Both produce compliant invoices. The difference is fit, not compliance.
Choosing without checking your POS
Your POS or integrator usually determines which control unit fits. Decide with them, not in isolation.
Ignoring volume
A unit that suits a low-volume till may not suit a high-volume integrated system. Match it to your invoicing.
Skipping KRA confirmation
Options change. Guidance written for an earlier revision stays online and reads as current, which is the main hazard when researching this.
A worked example
A growing business moved from a single phone till to an integrated POS across several branches and had to choose a control unit.
At a single till, a device-tied online control unit had been fine. With an integrated, multi-branch system and far more invoices, a virtual control unit fitted the integration better. Their integrator set it up, and invoicing scaled smoothly.
The right control unit followed the setup and volume. As the business grew, the answer changed.
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 helps
Veira sets up the right control unit for your business as part of onboarding, so you do not have to decide the technical detail yourself. Invoices sign and transmit correctly whether you run one till or several.
You get compliant invoicing without needing to understand the control unit mechanics. See how Veira works or book a demo.