What are the best options for getting a marriage or retirement visa in Thailand before my current visa expires?

For very basic official information you can check here (No.18 for marriage to a Thai national, No.22 for retirement). Each office has additional requirement as proof of these criteria, so as

@Benj****

says, check your local immigration office for detail.

@War***

, First of all, you NEED to check your used visa sticker if it has notes (typed or handwritten) which says something regarding marriage/Thai wife. If this thing's written, you would NOT be able to apply for extension based on any other reason than being marriage to Thai national. If nothing written, you could have some choice from reasons for Non-O.

You may confused the date of visa expiry and admitted to stay until date on entry stamp. check and be sure what you have now...

Third solution is an income letter from your embassy with confirmed income of at least 40.000 Baht! Some embassies are still confirming it!

Retirement visa easier and faster

Where are you intending to live? Best strategy is find a Facebook group in that area (there will be one trust me), and ask all the questions there, as they will have the answers specific to that immigration office

When you enter on a Non-O visa, you're stamped in for 89 days. You're in quarantine for 15 days, so you should have 74 days remaining on your stamp.

>Where would I find the official website to find this information?

Each immigration office will have their own requirements to get a one year extension of stay based on marriage OR a one year extension of stay based on retirement. You'd have to ask the immigration office.

>Just wondering which option is the easiest and quickest.

Both are equal in difficulty, I think. For the extension of stay based on marriage, you'll have to keep 400K THB in a Thai bank account, while for an extension of stay based on retirement, you'll have to keep 800K THB.