The phrase government-issued identification number is intentionally broad. Depending on the country and the situation, it may refer to a passport number, driver’s license number, social security number, tax identifier, or another official code assigned by a public authority.
There is rarely a single universal number that works across all systems. Instead, governments issue multiple identifiers, each designed for a specific purpose. Public registries, tax authorities, licensing bodies, and immigration services all rely on different numbers to reference official records.
This guide explains what a government-issued identification number is, how it differs from an identity document, common examples from around the world, where to find these numbers, and how they are typically verified in practice.
What is a government-issued identification number?
A government-issued identification number is a unique identifier assigned by a public authority to link an individual or organization to an official record.
These identifiers support a wide range of government functions, including taxation, social services, healthcare, licensing, immigration, education, and voting. The specific number that applies depends entirely on the system being accessed and the purpose of the request.
There is no single “correct” government-issued ID number in the abstract. The correct one is the identifier used by the relevant authority for the task at hand.
Number vs. document: what you present vs. what gets recorded
On its own, an identification number rarely proves someone’s identity. While it allows a system to reference a record, it does not confirm that the person presenting the number is its legitimate holder.
For that reason, identification numbers are usually presented together with a government-issued ID document that displays the number. Depending on the context, this may be a passport, national ID card, residence permit, or driver’s license.
The document provides the physical or digital evidence, while the number acts as the link to the underlying record.
Government-issued identification number vs. SSN
This question most often arises in the United States, where the Social Security Number is widely used, and SSN verification is common across many onboarding and compliance processes. In this context, the distinction is simple: a government-issued identification number is a category, and the SSN is one example within that category.
An SSN is frequently used for employment, taxation, and financial services in the US, and SSN verification plays an important role in these workflows. However, it is not universal even domestically. Many organizations rely on other identifiers, such as driver’s license numbers or passport numbers, depending on the use case.
Outside the US, SSNs and SSN verification are not used at all. Other countries instead rely on national population registry numbers, tax file numbers, or identity card numbers as their primary identifiers.
Examples of government-issued identification numbers worldwide
While naming conventions vary, most government-issued identification numbers fall into three broad groups: population registry identifiers, tax-focused identifiers, and document-specific numbers.
National or population registry identifiers
India: Aadhaar
Aadhaar is a 12-digit number issued by the Unique Identification Authority of India to residents of India.
Sweden: Personal identity number (personnummer)
Assigned to individuals registered in Sweden’s population register and issued by the Swedish Tax Agency.
Poland: PESEL
PESEL is a national population register number widely used in official and administrative processes.
Mexico: CURP
CURP is an 18-character alphanumeric code used as a primary identifier in many government interactions.
Singapore: NRIC / FIN
NRIC numbers are issued to citizens and permanent residents, while FIN numbers are used for many foreign residents.
Tax-focused identifiers
United States: Social Security Number (SSN)
Used in taxation, employment, and many financial workflows, and printed on the Social Security card.
Australia: Tax File Number (TFN)
A personal reference number issued by the Australian Taxation Office for tax and related services.
Germany: Tax identification number (IdNr)
An 11-digit number issued by the Federal Central Tax Office that remains valid for life and does not change with relocation or name changes.
Brazil: CPF
A unique tax registry number issued by Brazil’s Receita Federal and used across many public and private services.
Document-linked identifiers
Some identification numbers primarily identify a document, even though they also reference an underlying record. Common examples include:
- Passport numbers
• Residence permit numbers
• Driver’s license numbers, which are typically issued at the state or regional level
These numbers often change when a document is renewed or replaced.
Where to find your government-issued identification number
Confusion often arises because forms ask for a government-issued identification number without specifying which one. The most reliable way to identify the correct number is to look for contextual cues near the field, such as references to tax, payroll, benefits, travel, immigration, or identity documents.
Common places to locate an identification number include:
- The physical document itself, such as a passport, national ID card, or driver’s license
• Official letters or certificates issued during registration
• Government portals or online accounts, particularly tax authority systems
If the request is unclear, avoid guessing based on the label alone. First, identify which government system is being referenced, then use the identifier associated with that system.
How government-issued identification numbers are verified
Verification methods vary widely in strength, cost, and availability. The approach depends on the country, the industry, the legal framework, and how the data is collected.
The source of the number also matters. A number manually entered into a web form presents different risks than one extracted directly from an official document.
1. Basic validation
This is the most common and accessible form of verification. Systems check whether the number matches expected length, format, character set, and checksum rules, where applicable.
Basic validation catches typographical errors but does not confirm ownership. Despite its limitations, it is often used in low-risk workflows.
2. Authoritative matching
This method checks whether the number matches records held by an official or regulated source. It offers the strongest assurance but is also the most restricted.
Access typically requires legal authorization, contractual agreements, user consent, and strict data-handling controls. Availability varies significantly by country and sector, and it is more common in high-risk or regulated scenarios than in everyday consumer onboarding.
3. Document-based verification
Document-based verification focuses on the authenticity of the credential itself and the accuracy of the extracted data. It does not usually involve direct access to government registries, nor does it guarantee absolute confirmation on its own.
Instead, it increases confidence by verifying the document, reliably extracting the identification number, and detecting inconsistencies that often appear in altered or fraudulent IDs.
Modern ID verification software typically performs the following steps:
- Guides users through capturing a clear image of a government-issued ID
• Confirms the document is physically present using document liveness checks to prevent presentation attacks
• Identifies the document type using a template library and extracts data from the visual inspection zone
• Reads machine-readable features such as MRZ lines or barcodes when available
• Validates RFID chip data on electronic documents
• Compares values across visual, machine-readable, and chip sources and flags mismatches
• Runs authenticity checks against document security features and image patterns
Solutions such as Regula Document Reader SDK are widely used because they standardize data extraction across thousands of document types and support global verification workflows without relying on direct access to every government database.
A final note on government-issued identification numbers
A government-issued identification number is best understood as a reference to a specific system, not as a universal personal identifier. Effective identity verification depends on selecting the right verification method for the specific identifier and use case.
In many real-world onboarding and compliance workflows, document-based verification provides the most practical balance of reliability, scalability, and global coverage, especially when combined with other risk-based checks.