How Kenyan Businesses Track Separate eTIMS Invoice Series in One Set of Books

Under the electronic Tax Invoice Management System (eTIMS), the Kenya Revenue Authority (KRA) validates every invoice and gives it a number of its own. Each eTIMS solution keeps a separate number sequence A business that invoices through the eTIMS Client, a Virtual Sales Control Unit (VSCU) and an Online Sales Control Unit (OSCU) therefore runs three KRA series at once, alongside its own internal invoice numbers.

Managing these sequences comes down to three practices: giving each internal series a clear prefix, recording the eTIMS number against every internal number, and reconciling each series before the VAT return is filed. Sound eTIMS invoice numbering links each internal number to the correct eTIMS invoice number, so that every sale and Value-Added Tax (VAT) entry traces back to one source.

How does invoice numbering work under eTIMS?

Every invoice on eTIMS in Kenya carries two identifiers. These include the number assigned by the billing system and the number generated when the KRA control unit validates and signs the invoice.

The Control Unit (CU) invoice number follows the format set in the KRA technical specification for OSCU and VSCU. It combines the CU ID with a sequential receipt number, separated by a slash. For example: KRACU0400000078/2231. Receipt numbers run in an uninterrupted ascending series for each receipt type.

The validated invoice also carries the CU date and time, internal data, a receipt signature and a QR code. These elements confirm that the invoice is genuine and form part of a valid tax invoice in Kenya. A signed invoice cannot be edited. Corrections go through a credit note that refers to the original CU receipt number.

Why do multiple eTIMS solutions create multiple sequences?

KRA allows taxpayers to register for and use multiple eTIMS solutions simultaneously to generate electronic tax invoices. Invoices issued through different solutions remain accessible through the eTIMS online taxpayer portal, but each solution maintains its own invoice number sequence. Two rules follow, both confirmed in KRA’s official eTIMS guidance: 

• A credit note must be generated through the solution used to issue the original invoice. 
• A business using multiple solutions must therefore track which solution generated each invoice, so that any credit note is issued through the correct channel.

An example with three solutions

Consider a home appliance distributor with a head office and warehouse in Nairobi and a showroom in Mombasa. The business uses three eTIMS solutions for different invoicing workflows:

• Installation services (eTIMS Client): The Nairobi head office’s service desk invoices customers for installation through the eTIMS Client, a standalone solution for businesses that don’t run their own invoicing system at that location.
• Retail sales (VSCU): The Mombasa showroom’s cashier tills connect to the VSCU, which integrates the business's invoicing system with eTIMS and supports bulk invoicing, including when the system is not always online.
• Wholesale orders (OSCU): The Nairobi warehouse’s Enterprise Resource Planning (ERP) system is integrated with eTIMS through the OSCU, a solution suited to invoicing systems that operate online.

Each channel generates its own eTIMS invoice series. On one day, the business could issue receipt 2231 from the OSCU, 4512 from the VSCU and 101 from the eTIMS Client. In the books, these look like three unrelated runs, and the KRA number alone does not show which branch raised the sale. The mapping table below connects them:

How are internal invoice numbers different from eTIMS invoice numbers?

The internal number is the reference your business controls. The eTIMS invoice number is the reference KRA controls. Both appear on the final invoice but serve different purposes.

The KRA invoice checker displays both the CU invoice number and the trader system invoice number. The VAT return is prepopulated from transmitted data, and buyers cannot amend the Personal Identification Number (PIN), invoice date, invoice number or taxable value in prepopulated purchases.

Without the CU number, matching a KRA notice to a sale is slow. Without the internal number, the branch logic is lost.

How should a business design a clear numbering structure?

The internal series is the one part of eTIMS invoice numbering that a business designs for itself. A structured prefix lets anyone read the source of an invoice from its number. A practical format combines these elements:

• Document type, such as INV for tax invoices and CN for credit notes
• Solution, such as SRV for portal services, RTL for VSCU tills and WHL for OSCU wholesale
• Branch code, such as NBO for Nairobi and MSA for Mombasa
• Till code where several devices share one branch
• A fixed-width running number, such as 000001

Keep one internal series for each combination of solution, branch and document type. Decide in advance whether running numbers restart each financial year, and add a year marker such as 26 to the prefix if they do. A restart without one creates duplicate numbers across years.

Businesses with multiple eTIMS branches should fix branch codes when each location is onboarded. Never reuse an old code for a new location.

How should credit notes be numbered and referenced?

A credit note reduces or reverses a validated invoice, and KRA expects it to point back to that invoice. These rules apply to every eTIMS credit note:

• It must be issued from the same solution that issued the original invoice. An OSCU invoice cannot be credited through the Online Portal.
• It must refer to the CU receipt number of the original invoice.
• According to KRA guidance, credit notes on sales can be claimed within six months of the invoice date. 
• For a VAT-registered customer, the system checks that the original invoice number was declared in the relevant return.

For record-keeping, give credit notes their own internal series, such as CN-WHL-NBO-000087. Store the credit note’s internal and CU numbers against it, along with both numbers of the invoice it corrects.

How can multiple sequences be reconciled in the books?

eTIMS reconciliation across several series works best as a monthly routine completed before the VAT return is filed. Follow these steps:

1. Download the month’s invoice list from the eTIMS taxpayer portal at etims.kra.go.ke, which shows invoices from all solutions.
2. Split the list by solution and by branch or CU ID.
3. Export your sales register for the same period with the same split.
4. Match records on the CU number and confirm that the internal number, date and taxable value agree.
5. Sort each CU series in ascending order and check for missing or repeated numbers.
6. Compare matched totals with the sales prepopulated in your VAT return.

KRA allocates sales to a tax period by invoice date and not by date of transmission. An invoice dated 30 June that reaches KRA in July still belongs to June, so filter both lists on invoice date.

What numbering mistakes should businesses avoid?

Businesses should watch for these errors, which usually surface during a VAT review or audit:

• Duplicate numbers: Tills sharing a series without a till code will eventually repeat numbers.
• Manual resets: Restarting a series mid-year breaks the audit trail. If a reset is unavoidable, start a new prefix and record the reason.
• Unexplained gaps: Deleted drafts, failed transmissions and voided entries leave holes in the internal series. Each one should be logged.
• Credit notes in the wrong solution: The original invoice stays open until the note is raised from the correct solution.
• Recording only one number: Every query then becomes a manual search.

These errors affect both sides of a sale. Since 1 January 2024, expenses must be supported by eTIMS invoices before a business can claim them. A buyer who cannot trace a seller’s invoice may lose the deduction and dispute the sale.

How does accounting software manage invoice series?

Much of this discipline can be built into the billing system. Accounting software in Kenya that integrates with eTIMS should offer these capabilities:

• Automatic numbering series by branch and document type, with prefixes set once
• Separate voucher types for invoices, credit notes and debit notes, each with its own series
• A field that stores the CU number and signature returned by eTIMS against each invoice
• Mandatory linking of each credit note to its original invoice
• Exception reports for invoices pending transmission, rejected or missing a CU number

Software reduces errors but does not replace a weekly review of exception reports.

Running several eTIMS solutions is workable when every invoice that a Kenyan business issues traces to one solution, one branch and one internal number. The CU number is the reference KRA relies on, and the internal number is the one the business runs on. Both should be recorded on every invoice and credit note, and each CU series should be reconciled before the VAT return is filed.

TallyPrime supports eTIMS invoicing with configurable voucher numbering, so each branch and document type can follow its own series while invoices are validated with KRA from the same voucher. 

Frequently asked questions

1. Can a business have more than one invoice sequence in eTIMS?

Yes. KRA allows registration on more than one eTIMS solution, and each solution issues its own sequence.

2. What is the difference between an invoice number and an eTIMS invoice number?

Your invoice number comes from your billing system in the format you set. The eTIMS invoice number is assigned when the control unit validates the invoice. KRA verifies invoices using the eTIMS number, while customers usually quote the internal number.

3. Are gaps in invoice numbers a problem?

Gaps in invoice numbers do not always indicate non-compliance. A gap in the CU series may indicate a transmission or system issue that requires investigation with your integrator or KRA. A gap in the internal sequence may result from cancelled or unvalidated drafts. Document the reason for each gap and retain supporting records.

4. How should credit notes be numbered?

Use a separate internal series with a prefix such as CN. Raise each note from the solution that issued the original invoice and record that invoice’s CU number.

5. Can each branch have its own invoice series?

Yes. The eTIMS Client supports multiple branches and cashier tills, and system integrations can be configured per branch. A branch code in the internal prefix keeps each branch’s invoices distinct in consolidated books.

6. How do I find a missing invoice number?

Sort the series in ascending order and look for skipped values. Search the eTIMS portal for the missing CU number and check the draft and pending-transmission lists in your billing system. If the invoice exists in eTIMS but not in your books, record the sale.