What we call a Trademark Renewal can refer to two separate documents:
The first is officially called a Declaration of Continued Use. This document is filed only once, after the trademark has been registered for five years. Oftentimes, people will refer to this as a five-year renewal colloquially.
The other is simply called a Trademark Renewal. A renewal must be filed between nine and ten years after a trademark registers, and every ten years thereafter.
You must file a Statement of Continued Use between the 5th and 6th anniversaries of your trademark registration date. You must file a renewal before every 10th anniversary of your registration.
In short, you’ll need to file documents with the USPTO before the 6th, 10th, 20th, 30th, 40th (and so on) anniversary of your trademark registration date.
In order to renew a Trademark, you must be using it in the same way you originally applied. So long as the mark doesn’t change, and you are still selling the same products, you can renew the mark indefinitely.
The Coca-cola Trademark was Registered in 1892, and is still active and in good standing!
Generally, no changes are permitted to be made for the information about the trademark itself, yet you can update the correspondent information if needed.
If you do not file a renewal by the appropriate deadline, your trademark will become abandoned, and you will lose your federal trademark registration. You will have to either revive or file a new application in order to preserve your rights.
The government charges a fee of $650 per class to process a 10-year trademark renewal(Section 8 & 9), and $325 per class to process a declaration of use (Section 8) between the 5th and 6th year.