The RO will invite the applicant to correct defects in a priority claim (indicated in Annex A of Form PCT/RO/110) within a time limit of 16 months from the priority date or, where the correction would cause a change in the priority date, 16 months from the priority date as so changed, whichever expires first, provided that a notice of correction may, in any event, be submitted until the expiry of four months from the international filing date.
Upon receipt of a response to the invitation to correct defects in a priority claim, the RO checks whether the indications furnished by the applicant have been received within the applicable time limit and whether they comply with the formal requirements of Rule 4.10 (see GL/PCT‑EPO A‑VI, 1.1). If so, the RO follows the procedure laid down in GL/RO 170.
The RO notifies the applicant accordingly, using Form PCT/RO/111, and sends to the IB and the ISA, respectively, a copy of that notification as well as a copy of the corresponding sheet of the PCT request containing the corrections.
If the notice correcting the priority claim is received before the RO declares the priority claim void (see GL/PCT‑EPO A‑VI, 1.4.2) and not later than one month after the expiry of the time limit, the response is considered to have been received before the expiry of the applicable time limit.
R. 26bis.2(b), last sentence