Hi, thanks for the query,
before I try to help you plz help me confirm few of my assumptions which are as follows,
#1 U r individual living in India and is below 60 years of age.
#2 U r a salaried employee of Infy. and not a contracted professional, but is contracted professional w.f.to part time job. It is okay to not to disclose if you wish so.
If the above are correct thn,
following is your answer
# Any person like you is required to pay tax vide 3 ways in general 1. TDS, which is deducted and paid to govt. by the person from whom you are earning that income, it is governed by section 192 for Salary income n 194J for professional income.
2. Advance Tax which assessee i.e. you calculate on the total income for the year on an estimate basis and pay tax on that estimated income in three instalments in specified percentages of tax on total income, Viz. on 15-Sep-30%, 15-Dec-60%, 15-Mar-100% of total tax liability for that year.Any tax paid to the govt. upto 31.march is also considered as advance tax.
3. Self Assessment Tax- any tax paid after 31.3 will be considered as SAT.
Thus govt. assumes that assessee has a fair Idea of what his income is going to be in the coming year because it requires that assessee should have deposited specified percentages of total tax liability at the year end well in advance through TDS or Advance tax.
Now you have to take up a total of all your income reduced by certain investments and expenses u/s 80c etc. and calculate tax payable (hope you know the slab system which is upto 2.5lacs nil tax...next 2.5 lacs 10% tax...next 5 lacs 20% and on balance income 30% tax is applicable which is thn increased by surcharge if income is above 1 cr. and that total is again increased by 3% cess this total amount is tax payable by you)....reduce it by TDS deducted by deductor the balance is your tax liability payable by your self as advance tax or SAT....
If total tax deposited upto 31. march is less thn 90% of total tax liability thn there is provision for interest u/s 234B which asks for oayment of 1% p.m. or part simple interest on balance tax payable(thus you will have to pay interest on balance tax if it is not paid upto 31.march.16 for f.y.2015-16 )
Also in case if advance tax liability as reduced by tds is not paid on stipulated date thn interest u/s 234C will be charge for deferment of adv. tax @ 1%p.m. or part simple interest but here last instalment is reckoned upto the date 15.march.
now to conclude yes you can pay tax upto the date of return filing as self assessment tax but with it you would also be required to may some interest amount, thus if you wish to save interest and reduce your chances to be selected for scrutiny assessment pay an amount close to your balance tax liability today itself.
Thanks for reading, hope it helps if anything else please do write back. regards.