Submission Identification Number Law and Legal Definition

Submission Identification Number (SID) is an Internal Revenue Service (IRS) identification number that identifies a submission of return. A SID is present in all attachment files and many request and response messages. In A SID, the first six digits contain the Electronic Filer Identification Number (EFIN), the next four digits contain the year, the next three digits contain the Julian date, and the last seven digits contain a sequence number to uniquely identify messages sent within a day with.