Consultants, agencies and service firms often receive monthly retainers through M-PESA or bank transfer. The important job is to connect the commercial invoice, payment evidence and tax invoice correctly.
Create the invoice before asking for payment
The invoice should state the period, contracted service, amount, due date and customer account. The payment method comes afterwards.
Use a stable client or invoice reference
A business client may pay from a director's phone, finance officer's phone or company bank account. Do not use the payer number as the client identity.
Keep payment confirmation and tax invoicing separate
KRA states that persons engaged in business are generally required to onboard eTIMS and issue electronic tax invoices, subject to the applicable rules and exceptions.
The M-PESA receipt confirms a payment transaction. The merchant's eTIMS process handles the tax invoice obligation.
B2B retainers often need exception handling, not aggressive dunning
A late payment may be tied to purchase-order approval, client finance cycles or a disputed scope item. The billing system should surface the overdue invoice and evidence; account management can own the commercial follow-up.
Retainers often have commercial exceptions
A monthly retainer can change because of additional work, credits, a revised scope or an agreed pause. Create the monthly invoice from the contract rule, but allow an authorized adjustment rather than asking finance to explain every variance in a spreadsheet.
Match payments even when the sender changes
One month the client may pay from a director's M-PESA line; the next month finance may use a company bank account. The stable identity should be the client account or invoice reference, not the payment sender.
A useful B2B month-end view
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retainers invoiced for the month;
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paid by due date;
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overdue but under client-finance review;
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partially paid or disputed;
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payments received through a different approved route;
- tax invoices issued and linked to the commercial record.
Do not confuse dunning with account management
For a consumer membership, an automated reminder sequence may be appropriate. For a B2B retainer, the better next action after a missed due date may be an account-manager follow-up that references the purchase order, statement or agreed payment cycle. The billing system should expose the overdue state and history without forcing one recovery style on every client.
This is where structured billing still helps: it gives the account manager reliable evidence and stops duplicate follow-up after payment arrives.
Statements reduce B2B payment friction
For clients with several invoices or adjustments, provide a statement showing opening balance, invoices, credits, payments and closing balance. That gives the client's finance team a document they can reconcile internally before escalating a supposed missing payment.
Sources
KRA eTIMS overview: https://www.kra.go.ke/online-services/etims
KRA: What is eTIMS?: https://www.kra.go.ke/business/etims-electronic-tax-invoice-management-system/learn-about-etims/what-is-etims
