Methodology.

Where the figures come from

Sources are ranked, and a lower rank never overrules a higher one:

Rank	Source	What it settles
1	The statute — the Income Tax Act, the NSSF Act 2013, the Social Health Insurance Act 2023, the Affordable Housing Act 2024, and the amending Acts, read in consolidated form	Every rate, cap and threshold. If the Act states a figure, that is the figure.
2	KRA public notices	How the collector reads the statute — the Housing Levy base is the live example.
3	KRA guides and P10 documentation	Mechanics and filing formats. Guides have contained errors the statute does not; where they conflict, the Act wins.
4	Professional commentary — the large firms’ published analyses	A cross-check on our own reading, never a source of a figure.
5	Market practice — what payroll teams actually do	Noted where the law is silent; adopted only with the reasoning published.

Statutory positions are reviewed by XELQ Ltd, our statutory advisor, before publication. Figures still under review are marked on the page and are not printed as settled.

The same code

The calculators on this site are not re-implementations of our payroll app’s arithmetic. They import the same engine — the same statutory tables, the same rounding, the same order of deductions — that writes the app’s payslips, and a parity test suite fails our build if the two ever diverge. That engine’s KRA PAYE exports have come out byte-identical to real iTax submissions in parallel runs.

The tables are scoped to the payroll month, not the calendar year, because that is how the law works: Kenyan tables move in February, so January runs on the previous year’s figures. A calculator that only knows “this year’s rates” is wrong every January, and ours cannot be, structurally.

Reference figures the engine has no input for — mortgage interest, insurance relief, benefit valuations — are typed once, in one file, each carrying the instrument it comes from and the date it took effect. Nothing on this site is transcribed twice.

What we do when the law is silent

The worked example, in full, because the policy means nothing without one.

Overtime in the Housing Levy base. The Affordable Housing Act 2024 charges 1.5% of “gross monthly salary” and defines neither that phrase nor “employee”. KRA’s only definitional guidance is its 15 August 2023 notice — issued under the earlier Finance Act 2023 levy, and never restated under the current Act — which reads the base as basic salary plus regular cash payments, excluding non-cash benefits and income not paid regularly. The operative test is regularity: recurring overtime is arguably in, sporadic overtime arguably out, and that is inference, not quotation. Professional practice splits into a notice-tracking camp that excludes irregular payments and a market practice that includes overtime wholesale.

Our position: the engine includes overtime in the base — the conservative side — because the asymmetry decides it: under-remittance carries a penalty of 3% a month under section 9 of the Act, and over-remittance carries none. If KRA or the courts settle the question the other way, the engine changes, this page records the change, and the old position stays visible as a dated correction.

Under review — the questions we have not answered

Publishing an open question is not the same as publishing a guess. Each of these is with our statutory advisor now; none ships as a calculator input or a settled figure until it clears. The figures themselves, where an Act states one, are on the tax rates page with their instruments.

• Non-cash benefits above the exemption threshold (the threshold itself is settled): does crossing it tax the whole value, or only the excess? Either answer would change a benefits field, so no calculator here has one.
• The pension contribution cap (the figure is settled): does NSSF count inside the cap, or sit on top of it?
• Employer-provided housing: whether to model it at all, and on which valuation rules — the four statutory categories are printed on the rates page; the modelling question is separate.
• Which employee claims our advisor certifies for the app’s own inputs — mortgage interest, insurance relief, post-retirement medical fund. The caps are on the rates page; the calculator on /paye-calculator applies them as the Acts state them.
• Overtime in the levy base — the worked example above.

What this site is not

The calculators produce estimates for one employee, one month, on stated assumptions — each page lists what it does not model. Nothing here is tax advice, none of it substitutes for advice on your own circumstances, and a payslip is the product of a payroll run, not of a web form.

Tell us we are wrong

If a figure on this site disagrees with the Act, a KRA notice, or your P9, write to [email protected] with the source you are reading. Someone reads every one of these, and you will hear back within one working day. A confirmed error is corrected on the page, dated, and the correction stays visible — we do not silently overwrite a figure that someone may have already relied on.

Statutory positions on this page last verified against the Acts and KRA notices on 10 August 2026, by XELQ Ltd. Rates themselves are printed by the payroll engine, so they move with it.