Home MST (tax code) Vietnam
Vietnam MST (tax code) validator
How the MST (tax code) format works
- Format
- 10 digits (province code + serial number + weighted check digit), optionally followed by a 3-digit branch suffix
- Example
- 0100233488
Things to watch for
- This is a business/organization tax code (mã số thuế) — the 10-digit core is checksummed; a 3-digit branch suffix, if present, is not
- Often written with a dash before the branch suffix (e.g. 0314409058-002); strip separators before checking the raw digits
- Checksum only — a pass doesn't confirm the tax code is currently active with the General Department of Taxation
^[0-9]{10}([0-9]{3})?$Vietnam’s MST (mã số thuế, tax code) is a 10-digit identifier the General Department of Taxation (GDT) assigns to businesses, organizations, and registered business households, sometimes followed by a 3-digit branch suffix after a dash — for example 0100233488, or 0314409058-002 for a specific branch. It’s the number that appears on Vietnamese invoices, contracts, and tax paperwork, and getting it right matters for anything from e-invoicing systems to supplier onboarding.
Where the check digit sits
The 10-digit core carries the check: a province code and serial number make up the first 9 digits, each weighted by a fixed set of values, summed, and reduced modulo 11 to produce the 10th and final digit — which is what this tool recomputes. A 3-digit branch suffix, when present, identifies a dependent unit of the organization but carries no checksum of its own, so it isn’t verified here.
How this validator works
This tool accepts the MST with or without a branch suffix and with or without the separating dash, confirms the 10-digit core, and runs the GDT’s real weighted mod-11 formula against it — entirely client-side, with nothing sent to a server.
What a pass doesn’t tell you
A pass confirms the 10-digit core is internally consistent — not that the tax code is currently active or that any branch suffix attached to it is correct.
Scope: this page and tool cover Vietnamese MST format and checksum validation only — not live registration status with the GDT.
Content last reviewed 2026-08-09.
MST (tax code) FAQ
What is Vietnam's MST?
Mã số thuế — the tax code Vietnam's General Department of Taxation (GDT) issues to businesses and organizations, used on invoices, contracts, and tax filings. It's the standard way a Vietnamese company or business household is identified in a tax context.
What does the extra 3-digit suffix on some MSTs mean?
It identifies a dependent branch or unit of a larger organization, usually written after a dash (e.g. 0314409058-002). Only the 10-digit core is checksummed — the branch suffix, when present, is administrative and isn't covered by the check digit.
Does a valid checksum confirm the MST is currently active?
No. It only confirms the 10-digit core is mathematically consistent with the GDT's check-digit formula — not that the tax code is currently registered or active with the General Department of Taxation.