What is the “Window Period” for patent maintenance fee payments?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

The “Window Period” for patent maintenance fee payments refers to the specific timeframe during which these fees can be paid without incurring late fees or risking patent expiration. According to MPEP 2575:

“The ‘window period’ is the period of time at the end of the full term of a patent during which the maintenance fee can be paid without surcharge. The ‘due date’ is the last day of the ‘window period.’”

Specifically:

• First maintenance fee: payable at 3 to 3.5 years from the date of grant
• Second maintenance fee: payable at 7 to 7.5 years from the date of grant
• Third maintenance fee: payable at 11 to 11.5 years from the date of grant

Paying within this window period ensures timely payment without additional costs.