Income Tax Calculator India - Old vs New Regime
I developed Income Tax Calculator India as a self-built finance tool to help salaried individuals, freelancers, and tax planners accurately calculate their income tax under both Old and New regimes. The application uses the latest FY 2025-26 tax slabs and enables users to make informed decisions about tax planning and maximize savings.
Finance Tool / Tax Calculator / Web App
Self-built product / SaaS Tool
1 Week
Challenge & Goals
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Implementing accurate tax calculations based on complex FY 2025-26 tax slabs for both Old and New regimes
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Creating a comprehensive income input system covering salary, house property, capital gains, and other income sources
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Handling various deductions and exemptions correctly for accurate tax computation
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Building a comparison interface that clearly shows differences between Old and New tax regimes
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Generating detailed PDF reports with formatted tax summary and calculations
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Ensuring calculations are error-free and comply with latest tax regulations
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Creating an intuitive user interface that guides users through complex tax calculations
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Optimizing for mobile devices to reach users on any device
Solution & Implementation
I built the application using Next.js with React for the frontend, leveraging client-side calculations for instant results without server round-trips. Implemented a comprehensive form system with validation for all income sources including salary breakdowns, house property income, capital gains, and other sources. Created a dual-regime calculation engine that processes tax under both Old and New regimes simultaneously for easy comparison. Integrated jsPDF library for client-side PDF generation, creating detailed reports with formatted tax summaries, income breakdowns, and regime comparisons. Used Tailwind CSS for responsive design that works seamlessly across desktop, tablet, and mobile devices. Implemented real-time calculations that update instantly as users modify inputs, providing immediate feedback and enabling tax planning scenarios.
Features Delivered
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Side-by-side comparison of Old vs New Tax Regimes with clear visual differences
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Accurate tax calculations based on latest FY 2025-26 tax slabs and regulations
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Comprehensive income input fields covering salary, house property, capital gains, and other sources
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Detailed deductions and exemptions handling for Old regime calculations
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Instant real-time calculations as users modify inputs
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Downloadable PDF reports with complete tax summary and breakdowns
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Responsive design optimized for desktop, tablet, and mobile devices
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Form validation ensuring accurate data entry and preventing calculation errors
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Clear presentation of tax liability, effective tax rate, and savings potential
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User-friendly interface that simplifies complex tax calculations
Results & Impact
Quantitative Results
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Tax calculations processed in under 100ms
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PDF generation time under 500ms
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Page load time under 1.5 seconds
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Mobile performance score of 90+
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Zero calculation errors reported by users
Qualitative Impact
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Empowers users to make informed tax planning decisions
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Saves time by eliminating manual tax calculations
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Helps users identify optimal tax regime for maximum savings
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Professional PDF reports suitable for tax filing documentation
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Accessible tool for both tax experts and general taxpayers
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Self-service solution reduces dependency on tax consultants for basic calculations
Project Screenshots
Lessons Learned & Technical Insights
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Complex tax calculation logic requires thorough testing with multiple scenarios and edge cases
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Client-side PDF generation with jsPDF provides better user experience than server-side processing
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Real-time calculations enhance user experience but require careful state management to prevent performance issues
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Form validation is critical for financial tools to ensure accurate results and user trust
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Clear visual comparison helps users understand complex financial differences quickly
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Responsive design is essential for finance tools as users often access them on mobile devices
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Accurate tax calculations build trust and require staying updated with latest regulations
Technologies Used
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Next.js
React framework providing SSR capabilities and optimal performance for the web application
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React
Component-based architecture for interactive forms, real-time calculations, and state management
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Tailwind CSS
Utility-first CSS framework for rapid responsive UI development and consistent styling
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jsPDF
Client-side PDF generation library enabling instant report downloads without server processing
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