How is sole proprietorship taxed ?

Dear Rahul

As mentioned, Your friend is sole proprietor ...means individual not partnership firm.....ok

Income tax return will be filed with PAN of proprietor .

If your turnover(Sales) is not more than 1 crore and profit from business is more than 8% of gross receipt or turnover for the year

Your can file your return in ITR-4S or ITR -4, subject to other information

1. Income Tax Return will be filed in the name of " Sole Proprietor".
2. Due date is 31st July ( in case, no audit is applicable )
30th September ( if audit applies) .
3. PAN of Proprietor is Mandatory while filing ITR.

In case audit applies, you have to maintain books of accounts.
In case Gross receipt exceeds 10,00,000 or total income exceeds 1,20,000 in any of 3 years immediately preceding previous year. You have to maintain books of accounts.
and also Every person carrying on the Legal, Medical, Engineering, Accountancy or Interior Decoration or any other profession as notified by CENTRAL BOARD OF DIRECT TAXES (CBDT) are required to maintain such books of accounts & other documents as may enable the Assessing Officer to compute Assessee’s total income.