Sometimes your NAICS will be affected by the 5 year review that happens to the classification system.
If the year ends in 2 or 7, you can be assured the review will commence. Changes are solicited from the public through a notice published in the Federal Register. They explain what needs to be submitted, who it needs to be submitted to and when it needs to be submitted by. Generally, the public has up to 90 days after the notice is posted. The suggestions go to the proper committees of each of the three countries who are affected by this system to determine if they can accept the proposed changes. Then it is seen by another committed for final recommendations and changes to the NAICS manual. These changes are outlined in a new Manual that is released the year of the change.
You should review your NAICS codes every year to ensure your business is still classified the correct way. Always keep your NAICS codes up to date in SAM as well.