When should I file the demand for international preliminary examination with the EPO?

Pursuant to Rule 54bis PCT, you can validly submit a demand at any time prior to the expiry of whichever of the following periods expires later:

• three months from the date the ISR and WO-ISA was transmitted to you by the ISA, or
• 22 months from the (earliest) priority date.

This time limit guarantees that you have at least three months from the date of mailing of the ISR to decide on the basis of the results of the international search set out in the ISR and the WO-ISA whether you want to file a demand with amendments and/or arguments. If you submit your demand after this time limit, it will be treated as if it had not been submitted.