When do patents expire?

A patent is considered expired when its legal protection ends, either because its maximum duration has passed or the required maintenance (renewal) fees were not paid. Once a patent expires, the owner can no longer stop others from using, making, or selling the invention.

In most countries, patents last 20 years from the filing date.

However, the patent can expire earlier if:

• The required patent renewal fees are not paid on time
• The patent is voluntarily abandoned by the owner
• It is invalidated due to legal challenges
  

After a patent expires, the invention enters the public domain, meaning anyone can use it freely.