This may be a daft question and I assume the answer is yes, but this is Thailand so I'd better ask.

I've applied for first ever 1 yr extension to Non O visa (which expires on 24 Dec 2006).

Passport stamped 'Application of stay is under consideration. Applicant must contact this office again in person on 23 Jan 2007.

So does this mean I can now stay until 23 Jan?

The officer didn't make any new stamps in passport to specifically update the 'Admitted Until' date. Did he forget or are we now using common sense?

What would happen on 23 Jan if application was refused (the officer, incorrectly IMO, was unhappy I didn't show 400k in bank - just legit income > 40k pm)? I'm assuming a weeks' grace would be given...

Yes, the 'under consideration' stamp allows you to stay til January 23. On that day you might get another one, February 23 or extention granted til Dec. 2007 or, if application denied,

'must leave within 7 days'.

I would add that the 'under consideration' stamp for an extension based upon support of a Thai national is normal. The 30 days, or in many cases, 60 days, is to allow the immigration officers to check the facts of your application, e.g. that you actually support a Thai national at the address you have given.

However under the new rules there is no requirement to support - indeed the wife can now be the person with the income.

Don't be surprised if you get stamped with another 30 day under consideration stamp as well, it can take several months.

I would add that the 'under consideration' stamp for an extension based upon support of a Thai national is normal. The 30 days, or in many cases, 60 days, is to allow the immigration officers to check the facts of your application, e.g. that you actually support a Thai national at the address you have given.

...or what Sunbelt Asia hast posted on 2006-09-12 06:08:58 from the new rules after Oct 1.:

6. On extension of stay based support of a Thai national (Marriage visa), before if you applied for this extension of stay, you would get a 30 day consideration stamp. Once you return in 30 days you would get the one year extension. Now it will be the same as an extension of stay based on business with the norm of three 30 day consideration stamps. Immigration will go out and check to see if it’s a real marriage or a sham before issuing the one year.