as of

Hi all,

Is it okay to use the expression “as of …” in the presentt perfect in the following way?

As of January 20, we have not received your letter.

Thank you!

Aikamama

That’s fine.

Thank you Beeesneees.

If January 20 already passed and it is now February, still is it okay to say
“As of January 20, we have not received your letter.”?

For that to work, you would need to change the verb:
As of January 20th, we had not received your letter.

However, ‘as of’ is only usually used to indicate that something has not been received as far as the writer/speaker knows.
If you were writing to someone that far after the date, then normally you would not use ‘as of’ at all.
We have not yet received your letter, which was due on…

Thank you Beeesneees for the detailed explanation!
It has cleared all my confusion. Thank you!