You could apply an extention stay at every the checkpoint except at the Suvarnabhumi Airport Checkpoint.
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You could apply a re-entry permit at every checkpoint. However at Suvarnabhumi Airport Checkpoint would provide this service if necessary depend on officers approval.
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For a re-entry permit,if you are in Bangkok area and you have an Internet access, you could
fill in a TM.
8 form and send it to bkk1_reentry@immigration.go.th
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You should e-mail the completed form 1 day in advance.
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You have to submit a 2" photo and pay a permit fee at counter service, the Immigration Bureau (soi suanplu office.)
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Fee for re-entry permit:
1,000 Bahts for single
3,800 Bahts for multiple