@Kim *******
Most Thai embassies worldwide have discontinued handing out Non-O Dependent Visas. No more new applications possible.
You BOTH need to be over 50 years old, and you both need to apply for the 90-days Non-Imm-O Retirement Visa, each on his/her own, fulfilling the requirements of the e-visa system of the Thai embassy or consulate in your country.
You and your partner BOTH need a minimum of 800,000 THB in each one's Thai bank account in your sole names, seasoned for 2 months on the day you apply for the 1-year extension . .
Once you have set up your Thai bank accounts, you can start to transfer every month a minimum of 65,000 THB, proven it comes from abroad, into your accounts, for 12 consecutive months, not missing one single month.
You can then use a 12-months bank statement for the 1-year extension application in the second year. Once it got issued, you can both pull the 800,000 THB out of your Thai bank accounts