How many days would you get doing the border run? And does it begin on the date you cross or the date that your 30 day exempt expires?

Thanks much.

Did you know that you can have your first 30 day visa exempt entry extended at CM Immigration's Promenada office for another 30 days for 1900 baht? No need to wait until the final day -- the 30 day extension will be added to the date of expiration of your original entry.

Don't let the thread about CM Imm. Prom. office scare you off. All that nattering is about retirement extensions. The process of getting a 30 day extension for a visa-exempt entry is fairly straight-forward at the Promenada office. Show up around 8 am and get in the "tourist extension" queue. Be sure to bring something that has your current address in writing. You won't believe how many tourists have no idea of what to put on the form for their local address.

You'll need your passport, 1900 baht and a 4 cm x 6 cm photo, but the copy shop next door to Imm. can sort out the photo and copies for you for a couple hundred baht.

Thanks Nancy. I should have included a bit more info. It's a family of four, two adults, two children.
All US citizens. Came in 23 Nov, good until 23 Dec, but their flt back to US is 28 Dec, need 6-7 more days. If a run to MaeSai is possible, they might want to spend a day or two in CR, then cross to get an ext. Will that work? Same questions are my first post.

I think you should post your question in the "Thai Visas" subforum http://www.thaivisa.com/forum/forum/1-thai-visas-residency-and-work-permits/

There are recent reports that the Mae Sai border is closed for the sort of in/out border crossing you're proposing -- you'd be sent to do a 30 day extension at the Chiang Rai Immigration office. You might as well do it here in Chiang Mai.

They stopped letting people do that a few months ago, latest reports are only those with visa's that allow them to re-enter are allowed to do it.

Moved to Visa Forum

Check your messages for my reply to the one you sent.

No out/in crossings are allowed at Mae Sai. Nearest place is Chiang Khong to do one.

The 30 day extension is your best option.