Section 44ad

Well , when partnership firm follow presumtive taxation scheme u/s 44AD and  file its return ( BELATED OR NOT) no exepense will be allowed to it EXCEPT partners salary and interest on partners capital.

now the question  arise ; Do we need to calculate partner's salary as per 40(b) or not AND  calculate book profit for that?

YES , you need to follow 40(b) also. this is how all of this works out.

1 . calculate Deemed PGBP  = 8% of turnover

2. reduce interest upto 12% on capital from deemed PGBP you will get BOOK ROFIT for section     40(b)

3 . calculate allowable salary as per sction 40(b) on book profit .

4. calculate taxable income = (book profit - allowable salary)

5. ultimately calculate tax on taxable income.