Can my wife apply for a dependent spouse extension based on my retirement extension without her maintaining a separate bank balance?

Yes, your wife can apply as a dependent, but BOTH OF YOU need to have 800,000 THB EACH in the bank.

1.6 M THB in one bank account or 800,000 THB in 2 separate bank accounts. No way around that, to the best of my knowledge. It will be best to deposit the full amount as soon as you can. I had a regular retirement visa for 3 years, as a spouse.

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If your wife wishes to use QR codes for payments & have access to online banking, then she’ll want her own account. Bank accounts in Thailand are not really joint accounts, as only 1 person, the primary bank/ visa holder, can only have 1 email and 1 cell phone tied to 1 bank account that must match the name on the passport. Some banks, like SCB, will only give 1 bank account with 2 debit cards. (This means no online access for the 2nd party, but full rights to make payments & withdrawals with a debit card).

In my experience, Bangkok Bank and others will allow 2 different bank accounts, with the correct paperwork, at the time of your initial bank application.

My husband had SCB for years. Since they refused to give me my own account in my name at a later time when requested, I ended up using Bangkok Bank, once I realized I needed the extra payment options & online flexibility.

Currently if the spouse is 50 years old, or older, they are not issuing dependant visa extensions. They are requiring the spouse to get their own visa extension based on retirement.

I have been told only OA visa allows dependents

Marek Dziaduch if you both apply for Non-O visas based on retirement in Poland then the 1st extension of stay must be for the reason the visa is issued, so you will each need 800k baht in a Thai bank for that first year as your embassy doesn't issue income certificates. At the end of that first year your immigration office *might* allow your wife to change the reason for her extension to one based on being your dependant, but it's something you need to ask the specific immigration office