Basic - 13500/- per month, HRA - 6600/- per month, Conveyance - 9900/- per month, Sales incentive - 10000/- per month, OT- 2000/- per month ( not regular), PF Employer - 12% of 13500 = 1620/- per month, Statutory Bonus - say 12,000/- minimum wages @ 8.33% - 1000/- per month. Now the Total remuneration excluding OT is 42,620/- per month. 50% of 42620/- = 21310/- will be basic per month. 21310/- will be other allowances including Employer's portion of PF & Statutory bonus - to be distributed accordingly minimizing other allowances.
In case of OT & Sales incentive ( As both are variable ) as and when appear ( Sales incentive more than 10,000/- per month ) , the same will be proportionately divided in to 60 : 40 and 60% may be add back to basic in the particular month & 40% to other allowances ( OT, Sales incentive) to maintain 50:50 condition of the total remuneration.
In the above calculation Basic has crossed 21,000/- per month - may not be eligible for Statutory Bonus and the calculation needs to be changed accordingly.