I'm getting married next year to a Thai and want to get the 1 year extension after that happens. I'll be on a tourist visa beforehand. How many days left on that do I need so I can do this in Bangkok?

Ok now on to the requirements. I'm clear on the income thing so no need to discuss that. What is this whole wife's house book thing? She will have been living with me for nearly a year by the time we're married, in my rented condo.

What else will be required? We're marrying here in Thailand. Thanks a lot experts

You will need to go through 2 stage process to convert from tourist visa to Non-O to extension of stay based on marriage and must have at least 21 days remaining on your permission to stay at the time of application. Bangkok immigration will handle 2 step process, but not all immigration offices will. You may need to check. If a problem you should obtain single entry Non-O visa (rather than tourist visa) to avoid 2 step process. This will give 90 day permission to stay on entry and can move straight to application for extension of stay during the last 30 day of your permission to stay.

You will need to take with you to immigration the wife (for interview), her ID card, tabbien bahn (house book)*, marriage certificate, photos together around the home, map to home, completed application form TM7, copies of passport/TM6 departure card, current passport sized photos and completed Form TM 86 if converting from tourist visa. Conversion fee 2000 baht; extension fee 1900 baht. Some offices are now asking also for Kor Sor 2 (copy of marriage register) so best to check/obtain if necessary when you register your marriage at amphur. If using 400k bank funds option you will need a letter from bank confirming the account balance agrees with passbook balance. If using 40k/month income option you will need income letter from your embassy if income is from abroad, or tax receipts if income is from within Thailand.

You will get a 30 day under consideration stamp. Immigration will give you a date to go back and get the remainder of your extension. If you plan to travel during the period of the extension you will need to obtain a re-entry permit from immigration to keep your permission to stay alive. Fee 1000 baht single entry; 3800 baht multi entry.

* This is the blue house registration book that shows your wife's name. By law all Thai nationals have to be registered on someone's housebook, maybe that of her parents?

Don't worry about the days too much. The tourist visa itself can be extended by 30 days. After you get married you can get a 60 day extension based on your marriage, so you will have enough time.

Thanks for prompt replies gents. So for that housebook thing, is a copy of her page from the book ok?

Oh and can I apply for this visa in Bangkok even though she has house book from a southern province?

The book will be required for show and a copy for file. The reason for book is to help prove the ID card is not a 'copy'. It used to be required by every office but now only Immigration seem to require both.