What expiration date should I use for my online 90-day report in Thailand: my original OA visa or my current extension?

When filling out the online 90-day report, you should use the expiration date of your current stay, which could be your current extension of stay or the expiration date of your entry stamp from the original OA visa, depending on your current status. Note that the field is not mandatory as indicated by the absence of a red asterisk.