karanb192/itr-wala ? reverse-engineered prompt

Build me a terminal based Indian income tax filing tool for AY 2026 27 that helps a person file their ITR without needing to do the math by hand.

I want it to read the user’s Form 16 and AIS details, ask a few simple questions for missing deductions, validate the inputs carefully, and then compute tax under both the old and new regimes so it can clearly show which one is cheaper. The tax calculation itself should be fully deterministic and tested, with sensible handling for common things like salary, house property, capital gains, deductions, surcharge, cess, interest, and late fee. It should also tell the user exactly what to enter in the portal, and produce a clean filing summary they can follow step by step.

Please make it privacy conscious, keep tax math local, reject bad or suspicious input, and include a self test or demo command so I can trust the results before using it. If you need to check current filing rules or forms, look up the latest docs online.