What documents are needed for a non-immigrant O visa extension in Thailand?

To apply for an extension of a non-immigrant O visa in Thailand, your husband will typically need to prepare several key documents. These generally include: 1) A completed visa extension application form. 2) His current passport with the non-immigrant O visa. 3) A clear copy of the passport and visa pages. 4) Recent photographs (usually 2). 5) Proof of financial means, such as bank statements or income verification. 6) Depending on the purpose of the visa (such as retirement, family visit, etc.), additional documents may be required (like evidence of relationship for family-related extensions). It is recommended to check with the local immigration office for any specific requirements related to his case.