it is, but if a passenger doesn't see anyone there, a Thai Immigration Officer or anyone manning the counter, then go ask another Thai Immigration Officer that you want a Re–Entry Permit and they'll get someone there to get you one....
Go to International Departure Gate 2 when going to the Security Check at Suvarnabhumi Airport
Go to the Right at the Bottom of the Escalator after the Security Check
It's the easiest way to find the Re–Entry Permit Counter (they put the name "Re–Entry Visa")
You can bring a filled TM.8 Form to save 5 minutes to fill the form there
You can bring a passport-size Photo to save an extra 200 baht Service Fee
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if the Admins/Moderators of another Thai Visa Advice Q&A Facebook Group would permit me to share info about getting a Re–Entry Permit at Suvarnabhumi Airport as Bangkok has 2 airports and the OP didn't specify which airport....
you can only apply and get a DTV E–Visa from a Thai Embassy/Thai Consulate and Thai Embassies/Thai Consulates are outside Thailand
also, among other requirements, Thai Embassies/Thai Consulates are gonna ask for proof, evidence of current location (outside Thailand and inside whatever country/area any particular Thai Embassy/Thai Consulate has specific jurisdiction over)
Many Thai Embassies/Thai Consulates do have a disclaimer/notice to Not Submit an Application Too Early before planned/intended travel dates, regardless of the type and duration of the Thai E–Visa
"...
Do not apply for a visa earlier than 90 days before you arrive in Thailand. (The best time to apply for a visa is approximately 4 weeks before the departure date.)
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VISA PROCESSING TIME: 5-7 WORKING DAYS (UP TO 14 WORKING DAYS DURING HIGH SEASON)
Applicants are recommended to apply for the visa in advance at least a minimum of 2 weeks but not later than 10 weeks before the expected date of arrival.
Do not apply for a visa earlier than 90 days before you arrive in Thailand. (The best time to apply for a visa is approximately 4 weeks before the departure date.)
Unfortunately, you applied "too early" with the Thai Embassy in London for your Multiple Entry Tourist E–Visa, because they promptly processed your application and issued you a Multiple Entry Tourist E–Visa in early September (10 September 2025):
So, if you had applied a bit later, say this month (October 2025), then you would have seen your E–Visa Validity Dates that you had suggested....
Regardless, do understand the particular details and differences between Visa Validity and Period of Stay....