Can contractors report sales and remit fees on a contract rather than Special Item Number (SIN) basis?

The IFF clause specifies that contractors must report sales separately for each National Stock Number (NSN), Special Item Number (SIN), or sub-item. A contractor may consolidate fees for multiple SINs and/or contracts into one check provided that the check is annotated with the following identifying information:

(1) contract number(s)),

(2) reporting period(s)), and

(3) report amounts. There is no requirement to remit the IFF by individual SIN.