In e-News for Tax Professionals, the IRS has reminded taxpayers that July 1 marks the closing of several business payment P.O. Boxes (also known as Lockbox addresses), in the Cincinnati and Hartford areas. Payments will be returned to sender. No forwarding service will be offered.
IRS first made this announcement in January 2020. See IRS will be closing some P.O. boxes in July; won't forward checks.
IRS instructs taxpayers and tax professionals that, to help ensure timely receipt, they should check IRS's Where to File website before mailing tax payments.