Looks like the requirements have been stiffened since I last looked at this.

https://bangkok.immigration.go.th/en/visa-extension/#1610937437663-90b1feab-b48a

 

Can anyone shed any light on item #2 please - "Statement (No.3)"?

Maybe it's the one acknowledging overstay issues.  I recently did an extension and there were 3 "statement" documents given to me to fill in.  The document check people will provide it.

We complete 3 statements (Thai spouse).

1. Acknowledgement of the terms and conditions. (Statement 2)
2. Acknowledgement of the overstay rules.

3. More, an 'affidavit' the wife completes confirming the marriage is de jure and defacto.

I think item 2 relating to Thai child is their birth certificate.  

2 hours ago, colinchaffers said:

I think item 2 relating to Thai child is their birth certificate.  

Nope, that's 5, not included in the OP;

5)  Evidence of relationship

5.1 Copy of Birth certificate and household registration of Thai children

 

Thanks everyone. From the link I provided, item #3 is form STM2

Quote

3. Form for acknowledging the criteria and conditions required for temporary residence permission within the Kingdom. (STM.2)

So that still leaves the 3 items referred to in #2 outstanding.

 

I saw elsewhere that I need to take a letter from the wife, so that could be 1 of them, and I think there's another form for accepting the penalties for overstay etc - so that still leaves 1?