Is a hotel booking confirmation without payment sufficient for applying for a Certificate of Entry (COE) to Thailand?

A user is inquiring whether a hotel booking confirmation they received, which does not require immediate payment, is sufficient for applying for the Certificate of Entry (COE) at the Thai Embassy. Responses indicate that while some users successfully used such confirmations, others were required to provide proof of payment. Therefore, it's suggested to verify requirements with the embassy in case of hotel changes, as a new COE application would be necessary.