The term “government-issued identification number” is just as vague as it sounds. In any country or context, it could mean a driver’s license number, a passport number, a social security number, and many others.
What’s more, there is rarely a single universal code that works for every institution's request to provide this “number.” Instead, public record systems use different identifiers for different jobs.
In this short guide, we will cover the most common examples of government-issued identification numbers, where you can locate them, and how they are usually verified in the real world.
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What is a government-issued identification number?
A government-issued identification number is a unique identifier assigned by a public authority to link a person or organization to an official record.
As such, it can refer to identifiers used for taxes, social services, licensing, immigration, education, voting, and more. The “right” number depends on what system is being referenced and what the requesting organization is trying to do.
Number vs. document: What you show vs. what gets recorded
A number by itself rarely proves your identity. While it does enable matching of a certain kind, it is not the same as confirming that the person holding the number is the rightful owner.
That is why the number is often presented along with a government-issued ID that has the identifier printed on it. Depending on the context, the credential will vary, from a passport to a driver’s license.
Government-issued identification number vs. SSN: Are they the same?
This question often comes up in the US context, so it’s worth spelling out: government-issued identification number vs. Social Security Number (SSN) is a category-versus-example situation.
An SSN is one of many possible identifiers in the US. SSN verification is widely performed, but it is not universal even inside the country, and it is not the standard outside the US. Many other countries rely on a national population register number, a tax file number, or an identity card number instead.
Government-issued ID number examples around the world
Below we have collected some examples of government-issued identification numbers across different regions. They fall into a few common families: tax identifiers, national or population registry numbers, and numbers printed on travel or residence credentials.
National or population registry identifiers
India: Aadhaar
Aadhaar is a 12-digit number issued by UIDAI to residents of India.Sweden: Personal identity number (personnummer)
Sweden assigns a personal identity number to everyone registered in the population register, issued through the Swedish Tax AgencyPoland: PESEL
Poland’s PESEL is a population register identifier used widely in official processes.Mexico: CURP
Mexico’s CURP is commonly described as an 18-character unique identity code used for official identification in many processes.Singapore: NRIC / FIN
Singapore uses NRIC numbers for citizens and permanent residents, and FIN for many foreign residents.
Tax-focused identifiers
United States: SSN
In the US, the social security number is a key identifier in many workflows, and it appears on the social security card.Australia: TFN (Tax File Number)
The Australian Taxation Office describes the TFN as a personal reference number used for tax and related services, and explains how people can locate it through official online services.Germany: Tax ID (IdNr / Steuerliche Identifikationsnummer)
Germany’s Federal Central Tax Office (BZSt) describes the IdNr as an 11-digit number that stays valid permanently and does not change due to moving or name changes.Brazil: CPF
Brazil’s Receita Federal describes CPF as a registry that contains personal data and notes that the CPF number is unique for each person.
Credential numbers that travel with a document
Some identifiers primarily identify a document, even if they also connect back to a record:
Passport numbers (tied to a passport document).
Residence permit numbers (tied to a residence credential).
Driver’s license numbers (tied to a license credential, and, in the US, typically state-issued).
Where to find your government-issued identification number
Sometimes it may get confusing where to look for your government-issued identification number because many forms don’t specify which one they want. The quickest way to get it right is to look for context words near the field: tax, payroll, benefits, travel, immigration, or “ID document.”
Common places to locate a government-issued ID number:
On the physical credential (passport, identity card, driver’s license).
On an official letter or certificate issued at registration.
Inside an official online portal (some tax authority portals specifically provide instructions for that).
If you’re still stuck on where to find your government-issued identification number, stop trying to guess based on the label alone. Identify which system is being referenced first, then choose the identifier that belongs to that system.
Verifying government-issued identification numbers
There are multiple ways to verify government-issued identification numbers. There are many different checks with different strength levels, different costs, and different availability depending on the country, sector, and legal setup.
It also matters how the data arrives:
A number typed into a web form carries one kind of risk (typos, swaps, borrowed IDs).
A number extracted from a credential carries another kind (forgery, tampering, low-quality prints).
1) Basic validation: “Does this look like the right kind of number?”
This is the most common check because it’s easy and cheap. The system tests length, character set, checksum rules when applicable, and basic formatting.
It catches mistakes, but it does not confirm ownership. Globally, this is the default “verification” in many low-risk flows.
2) Authoritative matching: “Does this number match official records?”
This is the strongest check conceptually, and also the most limited in practice. Access often requires legal permissions, contractual onboarding, user consent, and strict data handling. Availability varies a lot by country and industry.
In some settings, organizations can validate submitted identifiers against official sources or regulated services. In many consumer onboarding flows, that kind of direct check is not routine; it’s more common in high-risk scenarios.
3) Document-based verification: “Is the credential consistent, and is the number captured correctly?”
This is where specialized government ID verification software is used. It’s important to note that it does not verify a number with 100% confidence on its own, and it typically does not mean a direct lookup in a government registry.
However, what it can do very well is raise confidence by checking the document, extracting the data reliably, and looking for inconsistencies that often show up in altered or low-quality IDs.
Here’s what such software typically does, even without being able to access every government database:
Guides capture of a government-issued ID to get a usable image.
Checks if the document is physically present through document liveness checks to protect from presentation attacks, such as an ID shown on a phone screen, a printed copy, or via injection.
Identifies the document type using a document template library, then extracts fields — including the government-issued ID number — from the visual zone and applies authenticity checks.
Reads machine-readable features where available, such as MRZ in passports and barcodes on many identity documents, and checks the data and format.
If the document includes an RFID chip, it validates its data and genuineness.
Compares values across sources (visual print vs. MRZ vs. barcode, and chip when available) and flags mismatches.
Runs authenticity checks tied to document security features and image patterns, sometimes using different light sources when supported by the hardware (for example, UV/IR checks), then returns structured results with reasoning.
Software like Regula Document Reader SDK is widely used because it standardizes extraction across many document types, and makes it easier to record what was captured. It also scales well for global flows, because the core task is document capture and data consistency, not direct access to every state registry.
A final word on government-issued identification numbers
A government-issued identification number is best understood as a pointer to a specific system, and not a universal personal label. One practical lesson on onboarding and verification design is to always try to match the verification method to the identifier.
In many everyday workflows, the most reliable step is to perform document-based verification using specialized software that authenticates the government-issued ID before attempting any deeper checks.
