Treasury Bill Calculator
CBK 91 / 182 / 364-day bills · exact pricing · net of 15% WHT 🇰🇪
Face value = the amount you receive at maturity. Minimum KES 100,000, then multiples of KES 50,000.
Enter the exact accepted rate from the CBK auction result
Net effective yield on the same cash, after 15% WHT, at the MMF and fixed deposit rates you set on the left. T-Bill is fixed & locked to maturity; MMF is variable but withdrawable in days.
How Treasury Bills work in Kenya
A Treasury Bill is a short-term loan to the Government of Kenya, issued through the Central Bank of Kenya (CBK). It is sold at a discount: you pay less than the face value today and receive the full face value at maturity. The gap is your interest. Because they are government-backed, T-Bills are the safest shilling investment available, the trade-off is that your money is locked until the bill matures.
Kenya issues three tenors, 91-day, 182-day and 364-day, auctioned by CBK (the 91 and 182-day weekly, the 364-day on the CBK calendar). This calculator uses CBK’s own pricing and applies the 15% withholding tax, so the numbers match what actually leaves and returns to your account.
The exact CBK pricing formula
Unlike a simple “discount×days” shortcut, CBK prices a bill at its present value:
Price = Face Value ÷ (1 + rate × days ÷ 365)
The interest is Face Value − Price, and 15% withholding tax on that interest is collected upfront, so the cash you pay is the price plus the tax. At maturity you receive the full face value, and your net profit is the interest less the 15% tax. The calculator shows every line so you can see exactly where the money goes.
Tax: the 15% you must not forget
Interest on Treasury Bills attracts a 15% withholding tax, deducted at source. It is a final tax, so you do not declare it again. This is the single most common mistake retail investors make, quoting the headline auction rate as their return when the real, after-tax yield is lower. Only investors with a valid KRA exemption certificate (such as registered pension schemes) pay 0%. The fully tax-free government securities are infrastructure bonds, not T-Bills.
How to invest through DhowCSD
The simplest route is CBK’s DhowCSD portal (dhowcsd.centralbank.go.ke) or the DhowCSD mobile app:
- Open a free CSD account with your ID and KRA PIN (no broker needed).
- Pick your tenor and place a non-competitive bid, you accept the weighted-average auction rate, which is what most retail investors should do.
- Minimum KES 100,000 face value, then multiples of KES 50,000.
- Pay for a successful bid via M-Pesa Paybill 200222 by 2pm on the settlement Monday.
- At maturity, CBK pays the face value straight to your bank account, or you can roll it over into the next auction.
You can also invest through your commercial bank or stockbroker, who acts as your custodian for a small fee.
T-Bill vs Money Market Fund vs Fixed Deposit
All three deduct the same 15% withholding tax, so compare them on net effective yield (the comparison panel above does this for your amount). A T-Bill gives a fixed, government-guaranteed return but locks your cash until maturity. A money market fund is more flexible, withdraw within days, start from about KES 1,000, but its rate floats. A bank fixed deposit is similar to a T-Bill but usually pays less and carries (small) bank risk rather than sovereign risk. Match the tool to the job: T-Bills for a lump sum you can lock away, an MMF for your emergency cash.
Frequently Asked Questions
What is a Kenya Treasury Bill?
A Treasury Bill (T-Bill) is a short-term loan to the Government of Kenya, issued through the Central Bank of Kenya (CBK). It is sold at a discount to face value: you pay less than the face value today and receive the full face value at maturity, the difference is your interest. Kenya issues 91-day, 182-day and 364-day bills, and they are considered the safest shilling investment because they are backed by the government.
How is the T-Bill price and return calculated?
CBK prices a bill using its present value: Price = Face Value ÷ (1 + rate × days/365). The interest (discount) is then Face Value − Price, and 15% withholding tax on that interest is collected upfront, so the cash you pay is the price plus the tax. Example: a KES 1,000,000 364-day bill at 8.97% prices at about KES 917,900; interest is ~KES 82,100, WHT ~KES 12,300, so you pay ~KES 930,200 and receive KES 1,000,000 at maturity.
Are Treasury Bills taxed in Kenya?
Yes. Interest on Treasury Bills attracts a 15% withholding tax, deducted at source on the discount. It is a final tax, you do not declare it again on your annual return. Only investors holding a valid KRA tax-exemption certificate (e.g. registered pension schemes) pay 0%. This calculator applies 15% by default; switch to “Exempt” only if you genuinely qualify. (Note: infrastructure bonds, not T-Bills, are the government securities that are fully tax-free.)
What is the minimum investment and how do I buy?
The minimum is KES 100,000 face value, then multiples of KES 50,000. The easiest route is the CBK DhowCSD portal (dhowcsd.centralbank.go.ke) or the DhowCSD app: open a free CSD account, place a non-competitive bid (you accept the average auction rate), and pay via M-Pesa Paybill 200222 by 2pm on the settlement Monday. You can also invest through your commercial bank or stockbroker.
When are T-Bill auctions held?
The 91-day and 182-day bills are auctioned every week; the 364-day runs on the CBK auction calendar. Bids typically close Wednesday/Thursday, results are published the same evening on the CBK website, and settlement (payment) is the following Monday. Always confirm dates on the CBK calendar.
T-Bill or Money Market Fund, which is better?
A T-Bill locks your money for the tenor at a fixed rate, ideal for a lump sum you will not need until maturity. A money market fund is more liquid (withdraw in days) with a variable rate, and a lower entry (from ~KES 1,000). Both deduct 15% withholding tax. Use the comparison in this calculator to see the net effective yields side by side for your amount.