The entry date and the exit date mean that how long your visa is valid in, so you can just enter and stay in Vietnam until its expiration.

For your question, you can’t exit later than the exit date because of the invalidity of your visa. If you are going to stay longer, you can consider to apply for visa extension via website of tourism agencies or renew it by leaving and re-entering the country.

In order to know more detailed guideline about how to apply for the approval letter as well as Vietnam visa, you can access our website or send us an email: info@vietnam-evisa.com