@joe s1 That's F.1116 Sch B you're referring to and that's for FTC carryover, not loss.

A statement for losses (i.e. SLL/OFL/ODL) does need to be attached to F.1116 but there is no standard format for it and the IRS' e-file schema was also not built to spot the omission of such a statement.

As for the perfection period for states, it vary quite a bit.  Some are more lenient than others and some do not provide any perfection period at all.  If your client's state return is with one of those that do not provide for any perfection period, it'd probably be considered late.  Here's a tabulation that may help:

https://support.cch.com/kb/solution/000032935/sw2662