SALT calculation help

[smithdk19]

I am trying to maximize the SALT deduction (10K) since I already qualify for itemized deductions.   I only paid 9K in state taxes and about the same in State sales tax, however I understand I can only use one or the other.

That said, I owe close to 4K to my state because state taxes weren't taken out of my military retirment pay check.  Shouldn't the amount I owe for state income tax (4K) count toward the SALT limit of 10K for the 2020 calculation?  Or will this amount only count toward my 2021 SALT limits next year?  

It seems like if I own for 2020 it should count on my 2020 return so I can get the full 10K deduction.  Right now I'm short of that and next year I'll certainly be over if the 4K I pay for 2020 taxes get added to my 2021 SALT limit.  

[BillM223]

"Or will this amount only count toward my 2021 SALT limits next year"

It only counts when you actually pay it...sorry.

[smithdk19]

I figured that would be the answer.   Thanks for the help