The short answer
both are an integration between your own software and eTIMS, and they differ in the invoicing rhythm they assume. The choice follows from how your business issues invoices: how many, how fast, and whether the connection holds while you do it.
Side by side
| System-to-system integration | OSCU (Online Sales Control Unit) | |
|---|---|---|
| Kind of thing | An integration between a business's existing software and eTIMS, rather than a separate place to go and type. | A control unit specification that integrating software is written against, not something a business installs by itself. |
| Runs on | Windows, a laptop, a desktop, a server | a server, Windows |
| Connection | Depends on setup | Needs the connection up |
| Invoice rhythm | Continuous and automatic | Each invoice, live |
System-to-system integration
Your own software talks to eTIMS directly, so an invoice raised in the system the business already uses becomes an electronic tax invoice without anyone re-typing it. Continuous and automatic. The invoice is a by-product of the sale rather than a separate task someone remembers to do.
OSCU (Online Sales Control Unit)
One of the two control units a system-to-system integration is built against. The online variant, which works with the connection up. Invoices as they happen, with the connection carrying each one.
How to choose between them
Our reading, not a rule. Nothing below is a statement of what KRA requires.
System-to-system integration gets awkward when
A business with no existing system, where there is nothing to integrate. Low volume, where the integration costs more than the typing it saves. A setup nobody maintains, because an integration that silently stops is worse than a manual process.
OSCU (Online Sales Control Unit) gets awkward when
Trading conditions where the connection genuinely drops, which is the problem the virtual unit addresses.
What the rules say
Stated by the publisher from the cited KRA material. Our reviewer has not yet re-checked it against the source, so confirm anything you are about to act on with KRA directly.
KRA identifies several categories of eTIMS solution, among them eTIMS Online, the eTIMS Client, eTIMS Lite, system-to-system integration, reverse invoicing and buyer-initiated invoicing. Which one suits a business depends on how it issues invoices rather than on what it sells.
Tax rules in Kenya change with each Finance Act and with regulations made during the year. Before acting on any figure, deadline or threshold, check the current position on KRA's own website.
This page explains how a requirement generally works. It is not tax advice, and it cannot account for the specifics of any one business. For a position you intend to rely on, confirm with KRA directly or with a registered tax agent.
Common questions
Which is better, System-to-system integration or OSCU (Online Sales Control Unit)?
Neither, as a general matter. They assume different invoicing patterns, and the one that suits a business follows from how many invoices it issues and how reliable its connection is.
When would System-to-system integration be the wrong choice?
A business with no existing system, where there is nothing to integrate.
How do I know this information is current?
Tax rules in Kenya change with each Finance Act and with regulations made during the year. Before acting on any figure, deadline or threshold, check the current position on KRA's own website.
Sources
- officialeTIMS (Electronic Tax Invoice Management System) — Kenya Revenue Authority, checked 2026-09-18
- officialKenya Revenue Authority — Kenya Revenue Authority, checked 2026-09-18