Does making a tax payment on 10-15-2021 to cover all federal taxes due stop a late filing penalty?  This is assuming tax return was extended and not filed until after October 15th.  I have a client who owes taxes, but will not be ready to file on 10-15-2021.  If they make a payment on 10-15-2021 to cover the expected taxes due will they be charged a late filing penalty.  I know they will have a late payment penalty and interest.