How do I claim priority to a PCT international application?

Claiming priority to a PCT international application can be done in two ways:

1. In a U.S. national stage application under 35 U.S.C. 371:
   • The priority claim is made in the PCT application
   • No further action is needed when entering the national stage
2. In a U.S. nonprovisional application under 35 U.S.C. 111(a):
   • File within 12 months of the PCT filing date
   • Make the priority claim in an application data sheet
   • Provide a certified copy of the PCT application (unless already filed with the PCT)

In both cases, the PCT application must designate the United States. The specific requirements are detailed in 37 CFR 1.55(d)(2) and (f)(2) for national stage applications, and 37 CFR 1.55(d)(1) and (f)(1) for applications under 35 U.S.C. 111(a).