If you go late, you could get deported. You'll be in the country illegally. Unlikely but a possibility.

What about getting an O-A for yourself. You are over 50 so should qualify. I believe your wife can be under 50 if she applies with you at your countries embassy. Check your countries Thai embassy Web site. This will give you a 1 year ME. No need to do any border runs. Come and go as you like.

As Tod said in the first reply, you can convert a tourist visa to a non-o in country.

OK now I see your confusion. The income letter is valid for six month from issue until you take it to immigration for your extension. The extension of stay lasts 12 months.

Australia is just a walk in for the income letter. They have stat decs there and a sample preamble. Just take your passport and proof of source.

Is your income coming from an Australian source? You need the letter annually when you redo your extension. You will need the non-o visa first which you don't need to be 50 for. The income letter lasts six months. You shouldn't need an agent if you have all your docs.

The income letter lasts six months.

So do you have something you can show the embassy to prove your income. I guess something sourced from Australia, but your Thai bank account may suffice.

He wants to do income and not money in the bank. You need to go to your embassy. It looks like you are Australian. So am I and have a retirement extension based on an income letter. You just go to the embassy and write out a stat dec and provide something that shows where the income is sourced from. This is a new requirement. Maybe your Thai bankbook would suffice or some statement from Australia. Say a payment advice from a real estate agent if you're living off rent, etc. The stat dec only needs to be a few sentences. The embassy has a sample of the preamble that you need to state. I think the fee is 500 baht.

O-A Visa granted in your home country. Slightly more difficult to get as you need a clean police report and a medical saying you don't have a few weird diseases. See your home country Thai embassy website for details.