The rules for immigration services are posted on the wall at Nong Khai Immigration. They say report to Bangkok, but if you live upcountry, do your 90 day report at the nearest Immigration office.

I may be wrong, but Im quite sure it also said, if there is no immigration office near you, you may report to your local police station. Anyone know about this?

90 day address reports are made only to Immigration if that is what you are talking about (TM47 form).

The report can be done by post.

Nong Khai immigration is also very strong on reporting your place of residence - which can be done at the local police station.

A number of people have been reported as being fined for not reporting.