The calculation next adds up all PTO taken to date, obtained from the entries in each period to the element of the plan's absence type. It then subtracts the amount of time taken to date from the gross accrual to date, to obtain the net accrual to date.
Gross PTO accrual = Accrued PTO + PTO carried over
Net PTO accrual = Gross PTO accrual - PTO taken this year
If your enterprise allows employees to purchase additional PTO or sell unused PTO, you can define elements to record information about purchased or sold amounts, query them in the Net Calculation Rules window, and select for the elements' input values, rules governing their addition or subtraction in the net accruals calculation.