FCinv and WCInv

when calculate FCFF, in the formula, FCInv and WCInv, it is the absolute value of FCInv and WCInv or it is the increase onf FCInv and WCInv compare to the previous year? the formula i have question is: FCFF=EBIT(1-tax rate) +Dep.-FCInv-WCinv thanks.

Subtract any increase in fixed assets (FCinv) add any decrease in fixed assets (-FCinv). Same for WCinv. FCinv and WCinv = change in FC and WC