What are the time periods for filing priority or benefit claims in U.S. patent applications?

The time periods for filing priority or benefit claims in U.S. patent applications vary depending on the type of claim and application. Generally:

• For foreign priority claims under 35 U.S.C. 119(a)-(d) and (f), the claim must be made within the later of 4 months from the actual filing date or 16 months from the foreign application’s filing date.
• For domestic benefit claims under 35 U.S.C. 119(e) or 120, the claim must be made within the later of 4 months from the actual filing date or 16 months from the prior application’s filing date.
• For international applications entering the national stage, special rules apply.

The MPEP states: “37 CFR 1.55(d) contains provisions relating to the time for filing a priority claim in an application filed under 35 U.S.C. 111(a) and in an application entering the national stage under 35 U.S.C. 371” and “37 CFR 1.78(d) contains provisions relating to claims under 35 U.S.C. 120, 121, 365(c), or 386(c) for the benefit of a prior-filed nonprovisional application, international application, or international design application.”

Note that these time periods are subject to the provisions of 37 CFR 1.55(p) and 1.78(k), which state that they are not extendable but are subject to certain exceptions.