Sorry, dont want to sound too negative, but the tax calculator is so simple it doesn't handle even the most basic stuff. I am guessing you have never paid tax at the income tax website. I would suggest you to go the income tax website and see the inputs that the calculator takes.
I did look at that and many other tax calculators, and some are so complex that people don't know what to put in. It's intimidating.
I built this for my needs. If you want it to handle HRA, or LTA, or income 1 crore and above, etc, that's an entirely reasonable point of view, and I'd welcome a pull request if you have the time.
But am I correct in my assumption that you have never paid taxes yet? :) Any one who has ever been on a payroll will know that the basic component is dynamic. Also I don't know anyone who does not claim any exemptions!
Ha ha, no I've paid a variety of taxes: income, professional, capital gains... I've been an employee and now a startup founder. I also help others with taxes.
The script does have a field for EMPLOYEE_TAX_DEDUCTION. It defaults to 1.6 lac, assuming 1.5 lac for 80C and 10K for the rest (like medical insurance under 80D or whatever). But you can change it to whatever number you want to include other exemptions like HRA and LTA.
I think some things like PF and HRA are calculated based on basic income, but I was able to approximate the calculation without bringing basic income into account. Salary for the purpose of PF is limited to 15K anyway.