1. Overview
Net Pay Kenya is a calculator‑first site focused on Kenyan tax, payroll and tariff rules. We document how our data is sourced, verified, and released so teams can trust what they see and audit changes over time.
2. Data Sources
We rely on official regulators and notices. Key sources include KRA, NSSF, SHIF (MoH), EPRA, CBK and Kenya Gazette notices.
KRA
NSSF
MoH / SHIF
EPRA
CBK
Gazette
| Source | Data | Frequency | Link | Notes |
|---|---|---|---|---|
| KRA | PAYE, VAT, reliefs | As announced | kra.go.ke | Gazette/circulars drive updates |
| NSSF | Tier caps, rates | As announced | nssf.or.ke | Tier I/II caps and rules |
| MoH / SHIF | SHIF % and guidance | As announced | health.go.ke | Policy updates, circulars |
| EPRA | Utilities tariffs | Monthly/As needed | epra.go.ke | Tokens, levy components |
| CBK | Rates/FX context | As needed | centralbank.go.ke | Context for finance calcs |
| Kenya Gazette | Legal notices | As published | kenyalaw.org | Effective dates authoritative |
| Safaricom | M‑Pesa tariffs | As announced | safaricom.co.ke | Official M‑Pesa fees and bands |
3. Change Detection
- Monitored sources: regulator pages, press releases, tariff files, Gazette notices.
- Cadence: daily/weekly checks and alerts.
- Signals triaged for impact and effective date.
4. Verification & QA
- Cross‑check against original schedules and official PDFs.
- Peer review for sensitive changes; dual‑entry where appropriate.
- Boundary tests for threshold values and rounding policy.
5. Versioning & Releases
We apply date‑stamped versions (YYYY‑MM‑patch) and publish a public Update Log entry per change. Hotfixes are noted and linked to the affected calculators.
6. Publication & Rollout
- Staging checks → release to production.
- Change banner chip on calculators; Update Log entry.
- Cache busting for PWA users to receive the latest tables.
7. Calculator Assumptions
PAYE & Net Pay
- Progressive KRA bands; personal relief applied after band tax, with disability exemption and other reliefs applied only where explicitly toggled.
- Monthly vs annual conversions follow regulator guidance; any differences from 12 × monthly are explained in calculator notes.
- Net‑to‑gross calculations use an iterative solver that inverts PAYE plus statutory contributions, within a small numerical tolerance.
NSSF
- Tier I and Tier II contributions applied up to current caps, with employee vs employer split shown where relevant.
- Pensionable base options (e.g. basic pay vs gross) follow official NSSF guidance and are documented in calculator notes.
SHIF & Housing Levy
- SHIF contributions use the published banded table for the chosen base income; exemptions are applied only where formally documented.
- Housing Levy is applied at the current statutory percentage on the applicable base, with employer and employee portions separated where required.
M‑Pesa
- Tariff bands are encoded directly from official Safaricom P2P, withdrawal and PayBill tables.
- Excise duty is applied to applicable fees only, not to the principal amount.
- PayBill tariffs (Business, Mgao, Customer) are modelled as documented in the M‑Pesa calculator assumptions.
- Fuliza and GlobalPay estimates use published percentages and FX mark‑ups and are presented as approximations.
VAT
- Standard VAT rate is applied unless a zero‑rated or exempt scenario is explicitly selected.
- Outputs are rounded to the nearest shilling for display; internal calculations may use more precision.
Loans
- Loans use standard amortisation formulas (reducing balance or flat as selected) and include Kenyan‑typical fees where documented.
- APR is derived via an internal rate of return (IRR) calculation over the full payment schedule.
8. Tests & Edge Cases
- Threshold testing at band edges (e.g., PAYE 24,000 / 32,333 / 500,000 monthly equivalents).
- Low/high salary scenarios; solver tolerances for net→gross.
- Batch operations performance and consistency checks.
9. Transparency & Audit
- Public Update Log lists every calculator change with date and notes.
- Per‑calculator “Updated” chip shows the latest effective date.
- Where needed, URLs support version pinning (query string).
10. Contact & Feedback
Spotted an inconsistency or want to suggest an improvement? Reach out to us.
Contact: /pages/contact.html
Related documents: Update Log, Privacy Policy, Cookie Policy, Terms of Service.