Going back to PPP forgiveness crossing years - not an easy answer as it has 1040 basis considerations:  I am waiting for guidance and putting my clients on extension, if necessary.  Here is why it matters to my S-Corp clients:

If I deduct the expenses in 2020, without the PPP forgiveness (as it occurs in 2021) = negative stock basis, resulting in 1040 suspended losses, resulting in my clients paying more in individual taxes in 2020.

IF the PPP forgiveness is forgiven in 2021 and allowed to be recognized in 2020 = positive stock basis, allowing 1040 losses to flow through on Sch E page 2, thus matched expenses and lower individual taxes in 2020

If the PPP forgiveness is forgiven in 2021 and not allowed to be recognized until 2021 = suspended losses in 2020 are then released on the 2021 1040...not horrible, but not ideal