You can calculate PCB calculation by using PCB formula.
In OC PCB formula is same as LHDN Calculator wich is:
Net MTD = [((P-M)R + B - ( Z + X) )/n+1] - Zakat for current month
*(P =Total chargeable income)
For a year exclude [∑(Y-K)+(Y1-K1)+[(Y2-K2)n] + (Yt-Kt)]-(D+S+Du+Su+QC+∑LP+LP1) where (Yt-Kt) = 0
You can also simplify go to PCB table which is in 'Payroll' > 'Salary Slips' > 'PCBDetails'. Refer figure below :
