It is, however, not just banks on the receiving end. A perusal of various cases at the commercial court shows that judges are also demanding detailed, verifiable evidence from borrowers claiming banks overcharged them.

The pattern appears in at least 10 cases involving lenders like HFCB Kenya (formerly HFC, Housing Finance and HF Group), CFC Stanbic, African Banking Corporation, Consolidated Bank, National Bank, Kenya Commercial Bank, Stanbic, among others.

In November 2025, the High Court ordered Housing Finance to reconstruct two mortgage accounts belonging to Wilson Kirungie and Josephine Wanjiru and, if disputes remained, have them independently audited.

The court found that increasing arrears interest to 26 percent without notice and contrary to contractual and statutory requirements was unlawful, and any balances computed using such rate were invalid.

The court ordered a court-supervised reconstruction of the mortgage accounts secured by Nairobi apartments after the borrowers disputed the accuracy of the lender’s calculations and account balances.

Housing Finance had advanced Sh12 million and Sh9.1 million in 2010 and 2011. The borrowers challenged interest variations, payment allocation, statutory notices, and account accuracy.

The bank issued notices claiming arrears of Sh593,000 and Sh307,000, later increasing alleged arrears to Sh1.9 million and Sh1.1 million.

The borrowers paid Sh2 million and Sh2.5 million to stop threatened sales.

The court found increasing arrears interest to 26 percent without notice was unlawful. It invalidated balances based on that rate and stopped sales pending accounting.

It also ordered refund of unlawful charges debited to their accounts, including recovery, legal, auctioneer, and valuation fees, as well as reimbursement of audit costs.

The court ordered interest calculated on daily cleared balances using a 365-day year and monthly rests. The bank was required to reconstruct the accounts, with an independent auditor appointed if disagreements remain.

Similarly, in the case of Benson Ndindi’s estate against HFCB Kenya, the court ordered a fresh independent audit of the loan account.

The parties were asked to appoint a joint accountant to examine the figures. The dispute arose from a 1991 mortgage for a Runda property.

The estate said HFCB increased interest from the agreed 18 percent to as high as 26 percent without four months’ notice required by the charge.

It also challenged penalty interest, default charges and other debits. The magistrate accepted an Interest Rates Advisory Centre (IRAC) analysis and ordered HFCB to refund Sh8.4 million plus interest from March 2000.

In July 2026, the High Court overturned the Sh8.4 million award because the IRAC report was flawed, but upheld findings that HFCB breached the agreement.

The High Court found the report lacked detailed calculations, overlooked a 2003 restructuring agreement and relied on borrower records without corresponding bank records.

The court also upheld findings that HFCB could not levy penalty interest, interest on arrears or default charges absent in the lending documents.

Elsewhere at CFC Stanbic Bank, two borrowers had a Sh10.5 million facility and challenged unilateral interest changes while the bank threatened to sell their security.

The High Court determined that 13 percent applied from drawdown to September 2008, and 15.25 percent thereafter.

A later taking of accounts required the Deputy Registrar to determine total payments and whether those rates produced an overpayment.

The registrar accepted the bank’s accounts after finding that contractual charges not invalidated by the earlier ruling could remain.

In that case, the court also addressed bank interest rate variations and communication with clients, ruling that newspaper advertisements are not an acceptable legal method to communicate or vary loan terms unless explicitly agreed upon in the contract.

“Lenders may argue that it is cumbersome to write to each of their individual customers to advise on the change of interest rates. To my mind, that cannot be acceptable for reasons that the lenders do enter into individual contracts with each of their customers, therefore having individual obligations,” said the court.

“Further, it is not every day that every borrower flips through the daily newspapers to see if his lender has effected changes of the rate of interest applicable to his borrowing,” it added.

In another case involving the Kenya Commercial Bank and a borrower named John Gatu, the High Court found that KCB unlawfully increased interest above the agreed 18 percent without approval then required under Section 44 of the Banking Act.

The court barred recovery of interest above 18 percent and penalties arising from the increase.

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It ordered an agreed accountant or auditor to take accounts at 18 percent and restrained KCB from exercising its statutory power of sale pending accounting.

This was after the plaintiff produced documents showing that he had repaid to the bank a sum of Sh4.4 million for a Sh2.6 million loan borrowed from K.C.F.C., a subsidiary of Kenya Commercial Bank Ltd, in 1988 and 1989.

On the other hand, the defendant also produced a computation showing that the plaintiff’s outstanding debt was Sh47.4 million.

Pending the outcome of the taking of accounts, the bank was restrained from selling the security.

Similarly, in a 2024 dispute between African Banking Corporation and one of its clients, the court examined claims of 20 percent commercial interest and 36 percent default interest.

The court rejected those rates, finding the borrower had not been notified of the change and holding that 13 percent was applicable.

It found claimed balances of Sh12.3 million and Sh11.4 million contained illegal charges and uncontractual interest.

The matter was sent back for taking accounts, removing disputed rates and penalties, including payments, and recalculating the amount due.

The customer complained that the money demanded was too much, while the bank complained that they were given a little.

“The interest rates applied are illegal and have no basis in fact and in law. They were never notified and as such cannot be applied. It is therefore clear that there was no basis for award of the prayer for application of interest rates at 20percent per annum and 36percent default interest,” said the court.

Another borrower, Oye Ashioya, sued the National Bank of Kenya seeking protection of secured property from foreclosure, saying he had serviced the loan but lacked updated statements showing its position.

The High Court in February 2026 upheld the need for taking accounts after considering the dispute over the amount allegedly outstanding.

It upheld the magistrate court’s decision requiring an account audit and issuing restraining orders against foreclosure, ruling that the bank failed to prove actual indebtedness.

“In cases of this nature, where a dispute is framed as being on accounts, the preferable thing should be for both sides to focus on the accounts, where the borrower should file accounts on what it alleges it has repaid, with the lender filing accounts on what it has received from the other side, and on the balance outstanding, demonstrating how that outstanding amount has been availed at. That is what would resolve the matter,” said the court.

A borrower named Martin Fundi sued Consolidated Bank after the lender claimed a debt of Sh36.9 million secured against property in Embu.

He sought an injunction against sale and an order for accounts to establish the correct amount owed.

The court declined the temporary injunction sought on the evidence presented, illustrating that requesting accounts does not stop enforcement.

In the case of Joseph Mwangi against Kenya Commercial Bank, the borrower took a Sh500,000 loan in 1997 and said he repaid it within 36 months and overpaid by Sh22,000.

KCB demanded Sh397,243 and threatened sale. The High Court granted an injunction and directed accounting concerning alleged dues and the loan status.

Similarly, Housing Finance was found in 2019 to have varied interest without proper notice on an amount advanced to Peter Ludavaa.

The court ordered an audit. Two accountants appointed by the parties produced reports agreeing that the borrower had overpaid Sh629,583.

The court awarded that sum with 12 percent annual interest from April 5, 2004, showing how an accounting order can produce a quantified refund.

Elsewhere, borrower David Mwaniki sued Consolidated Bank after he took two loans totalling Sh2.4 million and complained about double entries, uncredited deposits and interest increases.

He commissioned an Interest Rates Advisory Centre (IRAC) analysis, which calculated an alleged overcharge of Sh2.9 million. He sought Sh3.2 million in refund and related loss.

The bank disputed the methodology, saying the report omitted contractual charges of Sh1.2 million, used incorrect Treasury Bill data, and ignored contractual interest calculations.

The High Court dismissed the claim in September 2025, finding the recalculation unsupported by transparent methodology and inconsistent with the facility letters.

The judge said facility letters “are critical documents” because they set interest, fees, charges and repayment terms governing the lending relationship.

The court concluded that failure to account for those terms undermined the report and ordered no refund.

The Santowels litigation against Stanbic Bank adds a regulatory dimension. The borrower’s facilities dated from the 1990s, and the dispute included competing interest calculations and the legality of interest increases.

The Supreme Court in 2024 held that loan interest increases were subject to Section 44 of the Banking Act and required approval from the Cabinet Secretary responsible for finance.

“Interest rates on loans and facilities advanced by banks/financial institutions are subject to the regulatory process under section 44,” the court declared.

Taken together, the court decisions show a judicial focus on the arithmetic behind disputed debts.

But the judgments also establish an important limit. A borrower’s audit is evidence, not a conclusion. Where methodology is incomplete, assumptions unsupported or contractual records ignored, courts can reject it.

For borrowers, the judgments underline the importance of facility letters, charges, statements, payment records and notices showing interest changes. For banks, they show the importance of complete, reconcilable records when balances are challenged.

The cases establish that where evidence raises a genuine dispute over how a debt was calculated, courts can require the bank’s figures to be tested, reconstructed or independently audited.

The emerging record puts mortgage arithmetic at the centre of disputes over interest, foreclosure and repayment.