Expensing deferred mortgage interest from Covid/CARES forbearance

[Stuart M.]

Say for 6 months in 2020 and 6 months in 2021 the mortgage on a SFH investment property was deferred under a CARES Act forbearance. 6 months into 2021 all the deferred interest and deferred principal were added to the back of the mortgage maturing in a few decades at 0% interest (the deferred RE taxes and property insurance were required to be paid back over 5 years at 0%.)

The 1098s have the full RE taxes listed on each of them. But they only have half a year each of mortgage interest listed on them. When is/was the proper time to expense the mortgage interest (and RE taxes and property insurance)? In the year it was accrued (even if on cash basis)? In 20 years when mortgage is paid off? What did everyone do?