Lending for months, not years
Treasury bills run 91, 182 or 364 days. You pay less than Ksh 100 now and are repaid the full 100 at the end — the gap is your interest. Sold every Thursday, and taxed at 15% on that gap.
The quoted rate is not what you earn. T-bills are sold at a discount, so the true gross yield runs 29 bps above the 8.7687% headline — then 15% withholding tax pulls the net to 7.66%.
And prices rose too. With inflation at 6.60% (CBK, 2026-08-31), the 91-day bill's 7.66% net leaves 1.00% in real buying power. Compounded, not subtracted: 7.66% − 6.60% would read 1.06% and overstate it.
Minimum Ksh 100,000, then multiples of Ksh 50,000 · next auction 2026-09-10
91-day bill: you keep 7.66% a year after tax, Ksh 9,092 in interest, Ksh 498,395 back in 91 days.
91-day bill breakdown
Discount basis: rate × days ÷ 365. Effective yield compounds the discount over a year; withholding tax applies to interest only. Rates are the last auction's weighted average (CBK auction, 3 Sep 2026, entered by hand) — the next auction will clear differently.
Rollover projection
Reinvesting net proceeds each maturity for 12 months
Cycles
4
Net interest earned
Ksh 38,214
Ends at
Ksh 538,214
Assumes the 8.7687% rate holds at every roll — the central risk of a rollover strategy. Rates reset weekly at auction, so a falling-rate cycle reduces the return shown here. Compare against locking a longer bond on the Ladder Builder.
Bill rates move with each auction. Follow Pesa Smart KE on WhatsApp and we post when they do — market news only, for everyone. Following tells us nothing about you: WhatsApp does not show us who follows a channel, so there is no number to give and no list to keep. Nothing you have entered on this page is sent anywhere.
Why the quoted rate is not what you earn
CBK quotes a true discount: the price per Ksh 100 is 100 / (1 + rate × days / 365), and the yield you actually earn is (100 / price) ^ (365 / days) − 1. Because you pay less than 100 and are repaid 100, the real gross yield sits above the headline rate — by roughly 29 basis points at 91 days, and under one basis point at 364, where there is nothing left to reinvest.
This page previously used the other convention — a bank discount on face value — and was marked verified while it was wrong. It understated the price and so overstated the return, by 84 basis points on the 364-day bill. The formula above reproduces all three tenors on CBK's own published results to four decimal places, which is the only reason to trust it.
Tax, and where bills differ from bonds
Interest on Treasury bills is taxed at 15% withholding, with no equivalent of the infrastructure-bond exemption. A bond and a bill showing the same headline rate do not pay the same, and on this page every net figure already has the 15% taken off.
How buying works
Bills are auctioned weekly, with bids closing Thursday at 2:00pm through DhowCSD. The minimum is Ksh 100,000, and above that in multiples of Ksh 50,000. The 364-day tenor is under notice — the National Treasury has said it intends to phase it out to shorten the debt profile — but it is still being auctioned and still being taken, thinly.
What this page cannot tell you
These are primary auction figures: what the government paid to borrow, on the day it borrowed. They are not traded prices, and we publish no secondary-market prices at all. If you need to know what a bill is worth to sell before maturity, this is not that number — and neither is any other figure on this site. See where every figure comes from.