Step 1 — Taxable Income: Gross salary minus NSSF contribution (NSSF is a pre-tax allowable deduction under KRA rules).

Step 2 — Tax Before Relief: Progressive bands applied to taxable income:
0–24,000 @ 10%  ·  24,001–32,333 @ 25%  ·  32,334–500,000 @ 30%  ·  500,001–800,000 @ 32.5%  ·  Above 800,000 @ 35%

Step 3 — Personal Relief: KES 2,400 credit subtracted from Tax Before Relief. Every employed person gets this by law — not optional, not per-person. Result cannot go below zero.

Practical result: Any staff earning KES 24,000 or below pays exactly KES 0 PAYE (the 10% tax equals the personal relief). A teacher on KES 15,000 pays SHA, NSSF, AHL — but zero PAYE. The system calculates this automatically; no manual toggling per person needed.