What happens to a Non-B visa if I exit Cambodia and return to Thailand without a re-entry permit?

When you exit Thailand with a Non-B visa and re-enter from Cambodia without a re-entry permit, whether your visa is automatically cancelled depends on specific circumstances. If you have been in Thailand for less than 90 days from your initial visa, there is no action needed. However, if you have applied for an extension at a local immigration office in Thailand, you must cancel that extension upon your return if you intend to apply for any future extensions. If you plan to return as a tourist without seeking an extension, you can leave the status as is.