@Lani ********
Great! What you want is for Person A to get a "One Year Extension of Stay Based on Being a Family member of a Foreigner who has Permission to stay in Thailand." [Note: I'm assuming the marriage is not a gay marriage; gay marriages are not legal in Thailand]
What someone needs to do is to go to the local immigration office and get the handout outlining the requirements. I do not believe there's any financial requirements.
Here's the process:
1. For both Person A [the person getting the new extension] and Person B [the one with the existing Non-B] to be there.
2. For Person A to cancel the current One Year Extension Of Stay Based on Employment, and then to apply for the One Year Extension of Stay Based on Being a Family member of a Foreigner who has Permission to Stay in Thailand.
3. Different immigration offices have different requirements, but expect the following requirements:
1. Person A's passport and a copy of:
- The data ["picture"] page
- The most recent visa
- The most recent entry stamp
- The departure card
2. Person B's passport [I don't think there's any copies needed]
3. A marriage certificate, and a copy of the marriage certificate showing that Person A and Person B are married.
4. POTENTIALLY a hand-drawn map to the house
5. 2x passport photos
6. The TM30 filed at the location where the people are staying.
7. 1,900 THB fee for the extension of stay.
OF COURSE, different immigration offices have different requirements, and may require more then the above. I do *NOT* believe there's any financial requirements.
Person A's Extension of Stay will be valid through the length of Person B's current extension of stay.