What steps do I need to take to obtain a retiree visa in Thailand and what are the costs involved?

All great info work on the bank account as soon as you arrive.

As you will enter on a single entry Non-O based on being over 50 (retirement), you will be stamped for 90 days upon entry into Thailand.

Then you will apply for a 1-year extension for the same reason (retirement) when your stamp remains 30 days or less (some immigration offices allow you to apply for an extension when you have 45 days or less remaining). Once you get a 1-year extension, you apply for a (multiple) re-entry permit to keep your extension when you travel out from Thailand. You can keep repeating the process every year as long as you meet the requirements.

You need to meet all requirements including financial, accommodation, etc, on the day of application.

This is the general information for retirement extension. You better go to the local immigration office as soon as you arrive here to get the latest requirements at that office, as detailed requirements vary by office.

Official fees regarding to the immigration office are:

extension: 1900 baht

re-entry permit: 1000 baht for single re-entry, 3800 baht for multiple re-entry