Reason Code 12818
The occurrence code 22 date must be within the statement covers period for all SNF TOBs (18x, 21x, 28x or 51x) unless the non-payment code is equal to C, N, or W. Then the date can be prior to the claim from date or after the claim through date.
For Occurrence Code 22, the date must be prior to or the same as the "From" Date in the Statement Covers Period field. It cannot be used on a no-payment bill.
CMS Internet Only Manual (IOM), Publication 100-4, Medicare Claims Processing Manual.