27 C.F.R. § 479.151
Failure to make returns: Substitute returns
If any person required by this part to make returns shall fail or refuse to make any such return within the time prescribed by this part or designated by the Director, then the return shall be made by an ATF officer upon inspection of the books, but the making of such return by an ATF officer shall not relieve the person from any default or penalty incurred by reason of failure to make such return.