I have to leave Thailand because of a death in the family. Unfortunately, my non-O visa will expire in 1 month. Most probably I will still be in quarantine after my return when the visa expires. Can I have the visa extended a month before the expiry?

Thank you for your feedback.

You can extend 30 days prior to expiry. 45 at some offices i.e CW.

I suggest you obtain your extension prior to leaving Thailand. 

Don't forget your re-entry permit before leaving..

If you are talking about an extension of stay you can extend it again 30 days before it ends and 45 days at a lot of offices.

16 hours ago, PedroBkk said:

Can I have the visa extended a month before the expiry?

Thank you for your feedback.

30 days before is the normal window, but at some Immigration Offices you can apply 45 days before, so it's depending of where you are staying, and at least one office prefers that you come only two weeks in advance, the latter is Samui Immigration.