On 1 January 2026, the Nigeria Tax Act 2025 replaced the old Personal Income Tax Act rules for salaries. Every payroll system in Nigeria had to change: the Consolidated Relief Allowance is gone, the first ₦800,000 of chargeable income a year is now tax-free, there's a new rent relief, and the bands are new. We build HR and payroll software at Orion Soft in Lagos, so we had to get this right anyway. We've now released the tax engine as open source, so nobody else has to rebuild it from the...