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Guam

Guam uses U.S.-style taxpayer identification numbers for Guam tax administration: SSNs for most individuals, EINs for business entities and certain other entities, ITINs for individuals who need a taxpayer identification number but cannot obtain an SSN, and ATINs as temporary identifiers for children in pending domestic adoptions.

GU GUM 4 TIN types Last reviewed 2026-05-14

TIN types

4 published formats. Open a type to see examples, structure details, and official sources.

Validate Guam TIN
Social Security Number (SSN)
Current Individuals

Social Security Administration (SSA)

Primary personal taxpayer identifier used on Guam individual income tax returns when the person has an SSN.

Details
Examples
001-01-0001
Where to find it

On the Social Security card and in Guam individual income tax return records.

Common names
SSN Social Security number
Structure
1-3 Area First three digits; no longer tied to geography under SSA randomization.
4-5 Group Middle two digits.
6-9 Serial Last four digits.
Official source
irs.gov ssa.gov secure.ssa.gov guamtax.com
Employer Identification Number (EIN)
Current Entities

Internal Revenue Service (IRS)

Business and entity taxpayer identifier used by the IRS and by Guam DRT services and forms when an EIN has been issued.

Details
Examples
12-3456789
Where to find it

On IRS EIN assignment records, Guam business filing records, and Guam GRT filing records.

Common names
EIN Federal Employer Identification Number Federal Tax Identification Number
Structure
1-2 Prefix IRS assignment prefix.
3-9 Entity identifier Seven-digit identifier assigned by the IRS.
Official source
irs.gov guamtax.com
Individual Taxpayer Identification Number (ITIN)
Current Individuals

Internal Revenue Service (IRS) / Guam Department of Revenue and Taxation (DRT)

Individual taxpayer identifier for a person who must furnish a U.S. or Guam taxpayer identification number but is not eligible to obtain an SSN.

Details
Examples
900-50-0000
Where to find it

On IRS or Guam DRT ITIN assignment records and related tax return records.

Common names
ITIN DRT ITIN Individual taxpayer identification number
Structure
1 Series Always 9 for this family of individual tax identifiers.
4-5 ITIN range Middle digits identifying the number as an ITIN rather than another 9-series tax identifier.
6-9 Serial Last four digits.
Official source
irs.gov govguamdocs.com
Adoption Taxpayer Identification Number (ATIN)
Transitional Individuals

Internal Revenue Service (IRS)

Temporary taxpayer identifier for a child in a pending adoption when the adopting taxpayers cannot obtain the child's SSN in time to file the tax return.

Details
Examples
900-93-1234
Common names
ATIN Taxpayer Identification Number for Pending U.S. Adoptions
Structure
1 Series Always 9.
4-5 ATIN marker Always 93 for ATINs.
6-9 Serial Sequentially assigned final digits.
Official source
irs.gov