For ex: My net/total Taxable Income, after all deductions, for the Financial Year 2016-17 is Rs 4, 00,000(4 Lakh Rupees).I am a salaried person.

Now, till 2.5 lakh, there is NIL tax. So, my taxable income left is 400000-250000 = Rupees 1,50,000(1.5 Lacs). I come under 10% slab , so now my income tax is Rs 15, 000.

I have not done any extra saving....now if want to open a PPF Account, then how much should i invest in PPF, so that i can save full RS 15000 tax or at least some part of it. I have declared in investment declaration form, that i will invest Rs 1.5 lac in declaration form. How does that matter?

Is it that to save just Rs 15,000 tax i have to put 10 times, 1.5 lacs in PPF account or i can just put 20000 - 30000 Rs to save full tax.

Is their some ratio 1:2 or 1:3..that means to save 1000 rs i have to invest 10000..etc..or something like that? Please help....im confused.

Thank you so much for your answer!