If I haven't paid any estimated quarterly tax payments for 2023 yet, can I pay all of them by the last quarter?

[Critter-3]

Well I am sure you mean 2022 estimated payments because the first 2023 estimate is not due until 4/17/2023.

So can you pay  all of the 2022 estimate using  the 4th quarter voucher ... YES.  Better to pay late then never however this may reduce an underpayment penalty but not remove it completely.  The IRS will bill you later for any penalty they deem appropriate. 

[francesdances]

I did mean 2022. Thanks so much, @Critter-3! Do you know if I should I write separate checks for each quarterly amount or 1 check for the total amount of all 4 quarters?

[JohnW152]

You may send just one check. 

Since the payments are being made past the due date, there's no need for multiple checks. 

However, before submitting a payment through the mail, the IRS suggests that you consider alternative payment methods. 

Please see Pay Online and other options in the IRS' Publication 505.