In most cases, you are able to extend and renew your visa once you are in Vietnam by submitting an application at one of the Immigration Offices. The extension you receive depends on the type of visa you already have. If you have a one-month visa, the extension will be for another month.
However, it is not always certain you can extend a visa since the Immigration rules are constantly changing. There are a few reasons for a visa extension refusal:
1. applicants overstay their visas.
2. applicants have problems with their past entries (overstay, wrong entry purpose).
As such, you are recommended to contact directly local Immigration Office in Vietnam to learn more on the matter, or kindly contact us via (contacts, email), we are pleasant to assist you with that to save your valuable time.