I suggest you go for a simple Payroll software which will solve all your trouble. We have excel formulas but I suggest you go with software such as Tally or other economical software. Choose a vendor who has been in this business for atleast 10/15 yrs and with good support team and who have option to update but you regularly on tax changes from time-to-time..
Usually most company in beginning of financial year say April/May13, will collect what we call "Investment Declaration Form" for Advance Tax calculation from staff who fall under taxable income. No poofs are required at this time, but it must be submitted compulsory around say Jan-Feb14.
Based on above declaration, Finance will compute the taxable income and deduct the same every month. In the event staff fail to submit the proof by Jan/Feb14, balance tax will be deducted within Jan-Mar14.
step 1 . every employee should be asked to inform you of the savings he is expected to do by 30 april
step 2 calculate the taxable income of each individual based on last year investments and savings .
step 3 pl include a formula to deduct 8% of taxable income / 12 .for those with income upto 3 lakhs
step 4 pl include a formula to deduct 16% of taxable income / 12 for income upto 5 lakhs
step 5 review the amount deducted by 1 jan .
step 6 increase or decrease the final amount and deduct it in 3 installments so that the employee is not burdened on 31 march .
step 6 inform the employee in pay slip the amount deducted and date of deposit to the it dept.