Paris Convention
PCT

National patents

Six months (internationally recognised exhibitions only)

Formal examination only.
Grant.

Duration is twenty years from the filing date of the application.
Annual maintenance fees are payable on each anniversary of the patent, the first falling due on the date of filing.
A six months grace period is provided for late payment.

Sufficient working to meet demand within four years of filing or three years from grant (whichever period ends later), failing which patent may become subject to grant of compulsory licence.