How is the effective filing date determined for claimed inventions?

The effective filing date for a claimed invention is determined as follows:

• The actual filing date of the application containing the claim, or
• The filing date of the earliest application for which the patent or application is entitled to claim priority or benefit

The MPEP cites 35 U.S.C. 100(i)(1): “the effective filing date for a claimed invention in a patent or application (except in an application for reissue or reissued patent) is set forth in 35 U.S.C. 100(i)(1) as: (A) if subparagraph (B) does not apply, the actual filing date of the patent or the application for the patent containing a claim to the invention; or (B) the filing date of the earliest application for which the patent or application is entitled, as to such invention, to a right of priority under section 119, 365(a), 365(b), 386(a), or 386(b) or to the benefit of an earlier filing date under section 120, 121, 365(c), or 386(c).” (MPEP 210)