Claiming priority more than 12 months after filing date of a first application ?

Understanding how the right to priority works is one of the basic skills of a patent attorney (trainee). Let's face it, if you don't understand how that works you better not take papers C and D yet ...

Anyway, I can imagine there may be confusion about actually obtaining the right of priority to an earlier application and the claiming of said right. For a valid priority right you need to file your priority-claiming application at the latest 12 months after you filed the priority application.

If you file a PCT application after the 12 month period, but within 2m thereof PCT time limits will still run from the priority date nevertheless. But does that mean you have a valid priority claim ?   Find the answer including legal basis here.

Check for yourself if the EPC has similar provisions ...