What is the reason you'd wait until you go for your extension to get it taken care of?
Just going over and file a TM30 now so you have it out of the way?
The max fine is 1600 baht but they usually just charge you 800.
OR
have who ever owns where you live make a user name an profile, add the address and file a TM30 for you online at the link on the main immigration website ..
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