First thank you for the good job. My question is:

If a person above 50 is on retirement visa but the wife is below 50 then what kind of cheapest visa can she get to be valid for one year? I had a friend on the same visa but the police refuse to give her dependent visa and in the end she had to give more than 15000 Baht to get a one year visa.

Please advise what documents is needed to get a visa based on her husband retirement visa.

Thanks in advance.

It depends upon whether you are on a visa from an embassy or an extension of stay based upon retirement you obtained from immigration.

If on an extension of stay your wife can get an a extension as your dependent. To apply for a the extension of stay she will first need an entry from a non immigrant O visa obtained from and embassy or consulate.

Immigration will not do a conversion to a non immigrant visa entry based upon a dependent extension.. I suspect that is what somebody paid 15,000 baht for through an agent to get which means it was not done legitimately.