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Building TaxBook.pro: A Nigerian Personal Income Tax Platform

The Problem

Calculating Nigerian Personal Income Tax is confusing. Most people don’t understand tax bands, reliefs, or how PAYE works. Even worse, paying taxes through official channels like Remita requires navigating multiple portals and manual calculations.

I built TaxBook.pro to solve this — a modern, transparent platform that handles Nigerian PIT calculations, payments, and record-keeping in one place.

What It Does

TaxBook.pro is a full SaaS platform with:

Core Tax Features

  • Instant tax calculator using official Nigerian tax bands
  • Automatic relief calculations (CRA, pension, NHF, NHIS, life insurance)
  • PAYE and self-employed support
  • Visual breakdown of tax bands and effective rates
  • Multi-year comparison charts

Smart Automation

  • AI-powered payslip parser — upload a PDF or image, and AI extracts all your income and deduction data automatically
  • Tax savings recommendations based on your profile
  • Email scheduled reports (monthly/quarterly/annual summaries)

Payment Integration

  • Remita integration — generate RRRs directly from calculations
  • Webhook verification for payment status tracking
  • Secure payment history in your dashboard

Professional Features

  • Export to PDF, CSV, and JSON formats
  • Share calculations via public links
  • Keyboard shortcuts for power users (Ctrl+Enter to calculate, etc.)
  • Dark mode with Nigerian Green branding

Tech Stack

Frontend:

  • Next.js 14 (App Router)
  • TypeScript
  • Tailwind CSS
  • shadcn/ui components

Backend:

  • Next.js API routes
  • Supabase (auth, database, storage)
  • Remita API integration (payment processing)
  • Vercel serverless functions

AI & Processing:

  • OpenAI GPT-4 Vision for payslip parsing
  • PDF.js and image processing for document uploads

Infrastructure:

  • Vercel (hosting, edge functions)
  • Cloudflare (DNS, CDN)
  • GitHub Actions (CI/CD)

Key Technical Challenges

1. Nigerian Tax Calculation Accuracy

Nigerian PIT has complex rules with multiple reliefs and deductions. I had to:

  • Research official FIRS tax bands and relief allowances
  • Handle edge cases (minimum tax, gross income thresholds)
  • Validate calculations against real payslips

2. Remita Integration

Integrating payment processing required:

  • Secure credential management (env-driven, no hardcoded secrets)
  • RRR generation with proper error handling
  • Webhook signature verification for payment confirmations
  • Idempotency for payment status checks

3. AI Payslip Parsing

Getting reliable data extraction from diverse payslip formats:

  • Used GPT-4 Vision to read PDF-rendered images and direct PDFs
  • Structured prompts to extract specific fields (gross income, pension, NHF, etc.)
  • Fallback handling for unclear or missing data
  • Cost optimization (only parse when user uploads, cache results)

4. Shareable Calculations

Public calculation links needed to be:

  • Secure (no sensitive user data exposed)
  • Performant (static generation where possible)
  • Immutable (calculations don’t change after sharing)

What I Learned

1. Nigerian fintech requires local context
Using FIRS-approved tax bands and Remita integration made the platform trustworthy. Users want to see “official” calculations, not approximations.

2. AI can simplify tedious tasks
The payslip parser was a game-changer. Users love being able to upload a document instead of manually entering 10+ fields.

3. SaaS features matter
Export options, keyboard shortcuts, and scheduled reports might seem minor, but power users rely on them daily.

4. Secure payments are hard
Integrating Remita taught me a lot about webhook verification, idempotency, and handling payment state transitions safely.

Results

  • Live at taxbook.pro since December 2025
  • Handles calculations for PAYE employees and self-employed users
  • Remita payments working in production
  • AI payslip parsing with 95%+ accuracy on standard formats

What’s Next

I’m working on:

  • Multi-state support (Lagos, Rivers state-specific taxes)
  • Employer dashboard (batch PAYE calculations for companies)
  • Tax filing reminders (notifications before quarterly/annual deadlines)
  • Mobile app (iOS + Android for on-the-go calculations)

Try It Out

Visit taxbook.pro to calculate your Nigerian Personal Income Tax, or check out the platform features guide for a full overview.

Tech stack: Next.js, TypeScript, Supabase, Remita, OpenAI GPT-4 Vision
Live site: taxbook.pro
Status: In production, actively maintained