Thanks for your reply Alan. I have tried different combination of brackets and formating but always come up with errors.

Below is an example of the IF statements I'm trying to nest:

=IF(AND(E2>0,E2<=40),A8*D15)
=IF(AND(E2>=41,E2<=50),A8*D16)
=IF(AND(E2>=51,E2<=60),A8*D17)
=IF(AND(E2>=61,E2<=70),A8*D18)
=IF(AND(E2>=71,E2<=75),A8*D19)
=IF(AND(E2>=76,E2<=80),A8*D20)
=IF(AND(E2>=81,E2<=85),A8*D21)
=IF(AND(E2>=86,E2<=99),NA