The PCT application procedure comprises filing, international search, international publication, supplementary international search, international preliminary examination, and national phase.
All PCT patent applications are subject to search and examination. In the first phase, Chapter I, the International Searching Authority searches, ‘examines’ and issues a preliminary, non-binding opinion on patentability. The applicant does not respond/interact with the Examiner.
There is then an optional stage, Chapter II, where the applicant does interact with the Examiner and requests a Demand to request International Preliminary Examination and also request a supplementary international search.
This table presents countries that have a 31-month deadline for both Chapter 1 and Chapter 2. Other countries that have varying deadlines for both Chapters, please refer to: https://www.wipo.int/pct/en/texts/time_limits.html#EP