An ordinary business loss on an 1120-S would be carried through, and reported on, the K-1(s) to the shareholder(s).
Shareholders would calculate an NOL individually.
See https://www.irs.gov/publications/p536#en_US_2018_publink1000177318
Note that most taxpayers can only carry NOLs arising from tax years ending after 2017 to a later year (i.e., no carrybacks due tax reform - the Tax Cuts and Jobs Act (TCJA)).
See https://www.irs.gov/publications/p536#en_US_2018_publink10004278
What does this mean? Can you give an example with numbers?
(My understanding of carryforward is that NOL can only deduct from income that are in the future and the present, carrybackward : NOL can deduct from past income that didn't have enough deduction to be lowered https://xplaind.com/247520/tax-loss-carry-back-and-carry-forward)