Methodology

This page records calculation methods, source limitations and corrections. It is not a claim that every legacy input has been verified.

The core principle

A source label and date are not, by themselves, proof that a number is verified. Salary and city inputs currently fail the observation-level evidence standard and are marked illustrative only.

Three confidence tiers are used:

• High — a statutory rate, a published tariff, or a figure from an official instrument. These are exact and change only when the law changes.
• Medium — a compiled figure from multiple published sources that broadly agree, when observation-level evidence supports the compilation. Legacy salary amounts do not meet this standard.
• Low — an estimate where published sources are thin, conflict, or are out of date.

For the repaired tax calculator, the gazetted Nigeria Tax Act 2025 is the controlling source: rent relief is 20% of annual rent paid, capped at ₦500,000 (s30), subject to claims and evidence (ss31–32). Secondary summaries do not override the Act. See the tax guide for sources and the correction log.

Tax figures

The personal income tax bands come from the Fourth Schedule of the Nigeria Tax Act 2025, effective 1 January 2026:

These bands were corroborated across at least three independent sources before being published, because published summaries of the new law disagree with each other. Several widely circulated articles give the 18% band as ₦7,000,000 wide; it is ₦9,000,000.

Statutory rates used:

• Pension — 8% of pensionable emoluments (employee), 10% minimum (employer), per the Pension Reform Act.
• NHF — the confirmed monthly contribution entered by the user. The tool does not infer participation or a contribution base from basic pay; confirm these with payroll/FMBN.
• National minimum wage — ₦70,000 per month, National Minimum Wage Act 2024.

Order of operations

The take-home calculation runs in this order: gross → less pension → less NHF → less rent relief → chargeable income → progressive bands → PAYE. Net pay = gross − pension − NHF − PAYE. Pension uses the selected earnings base. Rent relief is not deducted again from cash. A sole steady employment salary at national minimum wage or less receives the separate employment exemption even without pension; other income and additional reliefs are outside the tool’s scope.

The Consolidated Relief Allowance is not applied, because it was abolished. For reference, the old formula was the higher of ₦200,000 or 1% of gross income, plus 20% of gross income.

Electricity tariffs

Corrected 28 September 2026: there is no universal national Band A rate or reliable national B–E reference-rate table in this tool. The replacement data is directly transcribed from five official NERC and LASERC September 2026 orders, with the scope stated in each document:

• AEDC Order 088: FCT and Nasarawa; Table 3 on page 7.
• Ikeja Order 093: IE service areas in Ogun only, not Lagos; scope on page 6, Table 3 on page 7.
• Eko Order 091: Eko service areas in Ogun only, not Lagos; scope on page 6, Table 3 on page 7.
• LASERC MKTR/011: IE Energy Lagos Limited (Ikeja), Lagos service area; Table 2 on pages 2–3, effective 1 September 2026.
• LASERC MKTR/012: Eko Power Limited, Lagos service area; Table 2 on pages 2–3, effective 1 September 2026.

The Lagos documents are available from LASERC’s official order register. Their listed rates match the corresponding Ogun schedules, but applicability is independently verified rather than inferred.

The electricity guide links the source PDFs and records the Ikeja document's internal August/September date inconsistency. Presets are limited to Non-MD, MD1 and MD2 in Bands A–E. They do not establish lifeline eligibility or special-agreement terms and are not a live nationwide tariff feed. Source URLs, page references, review date and PDF checksums are stored with the data.

Receipt mode starts without a rate; no national figure is silently assigned. It supports VAT-exclusive and VAT-inclusive rates and separately entered cash charges. A receipt records the charge but does not certify compliance. The standard 7.5% VAT assumption is from section 148 of the Nigeria Tax Act 2025; confirm transaction-specific treatment.

Band A–E minimum service commitments are 20/16/12/8/4 hours per day, respectively, under NERC's explanation. They are not guarantees of delivered hours. Classification disputes and remedies require the applicable regulatory process, not a calculator verdict.

Fuel prices and commute costs

Commute correction — 28 September 2026. The commute tool no longer preloads an unsupported pump price or maintenance allowance, calls a partial budget the true cost, or assumes that public transport is almost always cheaper.

The NBS PMS Price Watch, May 2026 report and workbook supply optional historical petrol benchmarks. The NBS catalogue dates publication to 24 June 2026. The workbook's Fuel MAY 2026 sheet has the national average in D41 and state/FCT observations in D4:D40. National average: ₦1,596.25/L; Lagos State average: ₦1,561.22/L. These are averages, not medians, current quotes or city/route prices. The verified observation month is May, not the September review date. We do not claim this is the latest published report.

Receipt mode starts with no price. Public-transport fares, efficiency, maintenance and other cost allocations are personal inputs, not invented survey observations. Source archive/workbook/PDF checksums and cell references are recorded in data/commute.json.

Distance is one-way kilometres × one-way trips per week × selected commuting weeks per year. Annual figures divided by 12 produce an average month. Fuel-only spending is separate from maintenance and other entered monthly costs. Unentered depreciation, finance, insurance and other ownership costs remain excluded. Fare comparison uses the reader's full one-way fare, including transfers, for the same trip count; it does not assign a state-wide average fare to a particular route.

Other tools' legacy fuel defaults are not certified by this commute update. Check their assumptions and use your current pump receipt; a historical benchmark is not a current buying price. A source label or review schedule alone does not establish that a price was freshly verified.

Cost-of-living scenarios

The legacy city inputs are not verified city-price data. Broad source references did not establish the observation set, sample dates or calculations needed to support the figures as national medians or measured city differences. They have been withdrawn from headline statistics and city rankings.

The old arithmetic is retained in clearly labelled, expandable illustrations for transparency:

`` legacy category illustration = illustrative anchor × scenario factor / 100 ``

Here 100 is an arbitrary baseline, not a measured Nigerian median. Converting an unsupported amount to an index does not make it evidence. Historical internal field names containing median remain for compatibility; they do not certify the values as statistical medians.

Legacy anchors: annual one-bedroom rent ₦600,000; alternative two-bedroom rent ₦1,000,000; monthly groceries ₦95,000, transport ₦45,000, data ₦15,000, and utilities ₦20,000. These are example parameters, not recommended budgets or current quotes. The illustration uses only one-bedroom rent in its subtotal, and excludes healthcare, school fees, generator fuel, debt, savings and upfront fees.

The live relocation calculator no longer uses city factors. It accepts your own monthly budgets and net income. It separates the income needed to preserve the same naira balance from the income needed to preserve the same expense-to-income ratio. Neither predicts employer pay or guarantees affordability.

Salary data

No verified market wage sample currently supports the legacy profession amounts. They are retained only as explicit arithmetic illustrations, not recommended negotiating ranges, observed medians, salary percentiles or seniority bands. City amounts were produced by multiplying these inputs by a city factor and rounding to ₦5,000. This does not measure wages in that city.

We have removed highest-paid-profession rankings and wage-versus-living-cost conclusions drawn from those same factors. Generating wages from a cost index and then using them as independent evidence of affordability is circular.

The reader-submission collection is inactive: there is no configured collection form or imported salary dataset. Its previous description overstated operational status. A future programme would need explicit consent, data minimisation, an actual verification procedure and a defensible publication policy. A statement that a contributor has a payslip does not verify the payslip or establish representativeness. See the submission-status page.

Correction — 28 September 2026

Earlier salary and city pages labelled derived figures as local medians, used unsupported city superlatives and sometimes described partial budgets as all-in costs. Those claims have been withdrawn. Titles, descriptions, visible answers and FAQ structured data now reflect the evidence limits. URLs are retained; this correction does not turn the old inputs into a verified research dataset.

Supporting guide corrections — 28 September 2026

Rent ratios are planning references, not safe ceilings. The rent tool separates annualised rent and other after-move expenses from actual entered fees/deposits, available savings and an independently entered pre-move saving capacity. A negative recurring balance is retained; zero income makes the ratio unavailable. No general fee percentage or lawful advance period is inferred.

The solar-sizing guide now matches its worked load schedule: 4,552 Wh/day and 592 W connected. At an example 1.25 multiplier the intermediate value is 740 W, rounded to 800 W by the tool's size list—not a certified buying recommendation. Discharge fractions, sunshine, losses and power margins are assumptions unless independently supported for the equipment and site. Battery-recovery time and true motor surge are not resolved by these simple formulas.

The CAC guide's fee entries cite the Commission's May 2025 gazetted schedule and its notice deferring implementation to October 2025, rather than unsupported all-in ranges. Current portal assessments and subsequent rules must be checked. No guaranteed filing times or blanket entity-eligibility claims are made.

Calculator arithmetic

All calculator logic lives in one file, assets/js/calc-core.js. It runs in your browser and in the build process, so the static worked example on each page and the live result from changing an input cannot disagree.

The formulas:

• Battery sizing — watt-hours ÷ (depth of discharge × inverter efficiency) × days of autonomy
• Panel array — daily watt-hours ÷ (peak sun hours × 0.75 derate)
• Inverter size — total connected load × 1.25 surge headroom, rounded up to the next standard size
• Solar initial simple payback — initial installed cost (including first battery) ÷ positive annual operating saving. Future replacements are excluded from this measure.
• Solar replacement-aware break-even — timed battery payments strictly before the endpoint are deducted from cumulative savings; the reported crossing must remain non-negative through the selected horizon. The cash-flow table and total horizon costs are separate outputs.
• Relocation: same cash balance — net income + destination monthly budget − current monthly budget, with required income floored at zero.
• Relocation: same expense ratio — net income × destination budget ÷ current budget; unavailable at zero current budget.

The solar scenario is undiscounted, holds running costs and replacement prices constant, and assumes the entered generator spending is fully avoided. Financing, inflation, residual value, inverter/panel replacement and continuing backup costs are not modelled. It is not an NPV or a complete ownership-cost estimate. See the energy guide for corrected examples.

Review cadence

Every data file records its as_of date, and the build refuses to render a page using a figure that has no source or no date.

Corrections

If a figure is wrong or stale, that is a genuine contribution. Email hello@naijacalc.ng with the figure, the source you think is correct, and the date.