405.02(a) Personal Checks
It is the practice of the USPTO to accept, as "conditional" payment of a fee, a signed uncertified check (e.g., a personal check). If an uncertified check clears, then the USPTO considers the fee paid as of the date it received the check.
However, if such a check is returned unpaid, then the fee remains unpaid, and the document that included the returned check is processed as though the fee had been omitted. See In re Paulsen, 35 USPQ2d 1638 (Comm’r Pats. 1995). See TMEP §405.06 for further information about processing checks that are returned unpaid.
Under 37 C.F.R. §2.6(b)(12), there is a processing fee for any check returned to the USPTO unpaid.