The Verdict: Need More Info
This turns on whether either of your spouse's parents was Thai when your spouse was born. If so, your spouse is Thai already, even without Thai papers; our descent quiz checks it.
Section 7(1) of the Nationality Act makes anyone born to a Thai father or mother Thai, wherever they were born, with no generational limit. Since 1992 that includes people born earlier to a Thai mother. Papers are evidence of the status, not the grant, and there is no deadline to register.
If your spouse is Thai, get them registered first, and the marriage routes open: a foreign wife of a Thai man can apply directly under section 9, and a foreign husband naturalises after three years on marriage extensions.
If your spouse is not Thai, the marriage routes are closed, and our skilled migration quiz is the place to start.