What are the requirements for obtaining permanent residency in Thailand as a Brazilian expat married to a Thai national?

You do meet some key requirements for Thai permanent residency, but not all:

You have a valid work permit and have been living and working in Thailand for 4 years, which meets the minimum 3 consecutive years holding a non-immigrant visa/work permit requirement.

You are married to a Thai national, which qualifies you under the family/humanity category.

You speak Thai well, which will help for the language test during the application interview.

However, additional requirements include:

You must have paid taxes regularly and show financial stability, often demonstrated by tax returns and salary slips.

You need to pass a Thai language speaking and listening test during the interview.

The application process is competitive with limited quotas annually.

You must prepare extensive documentation including passport copies, work permit, marriage certificate, financial statements, health certificate, and others.