New IFF Statement

[t1sys]

Hello

I have the following statement that is working fine however I would like to add an additional criteria to the statement:

round (IIF([PAYTYPE]<>'Stipend' ,IIF([PAYTYPE]='Ftn',((([ANNRATE]+([ANNRATE]* ToNumber([RATEINC])))/10)*261)*[PRORATESAL], ((([ANNRATE]+([ANNRATE]*ToNumber ([RATEINC])))*[AWARDHRS]/14)*365)*[PRORATESAL]),([ANNRATE]+([ANNRATE]* ToNumber([RATEINC])))*[PRORATESAL])+[TOTALL], 2)

I would like to include a new criteria, the above will be true if the [OVRRDSALARY] = '0', however if [OVRRDSALARY] > '0', then the result will be [OVRRDSALARY]

Is there anyone who can please assist.

Thanks