What are the valid middle digit ranges for ITINs?

The 4th and 5th digits of an ITIN fall in 3 ranges: 50-65, 70-88, and 90-99. Digits 66-69 and 89 are not used. Digits 00-49 are not used (these would overlap with SSN patterns). The IRS assigns middle digit blocks sequentially as it needs new number capacity. Some middle digit ranges have been fully assigned and are associated with specific expiration waves in the IRS renewal schedule.

Can you tell when an ITIN was issued by its middle digits?

Approximately, yes. ITINs with middle digits 70-72 were among the earliest issued (late 1990s to early 2000s) and were the first expired in 2017. Middle digits 78-80 were issued in the mid-2000s. Digits 73-77 and 81-88 were issued in later periods. Digits 90-99 represent more recent assignment blocks. However, exact dates cannot be determined from digits alone. Your CP565 letter shows the precise assignment date.

How do middle digits relate to ITIN expiration?

The IRS used middle digit ranges to schedule systematic ITIN expirations between 2017 and 2021. Middle digits 70, 71, 72, 78, 79, 80 expired in 2017. Middle digits 73, 74, 75, 76, 77, 81, 82, 83, 84, 85, 86, 87, 88 expired in 2018. Middle digits 90, 91, 92, 94, 95, 96, 97, 98, 99 expired in 2019-2021. If not renewed, these ITINs remain expired. Middle digits 50-65 are not part of the middle digit expiration schedule.

Does the second and third digit of an ITIN have meaning?

The 2nd and 3rd digits (positions 2 and 3 in the 9XX prefix) do not carry specific geographic or temporal meaning like the pre-2011 SSN area numbers did. They are assigned sequentially by the IRS as number blocks are opened. The combination of all 9 digits creates a unique identifier. The 2nd and 3rd digits simply expand the available number pool from 10,000 to 1,000,000 possible combinations per middle digit range.

How many ITIN numbers are possible with the current system?

The current ITIN numbering system supports approximately 60 million unique combinations. First 3 digits: 100 combinations (900-999). Middle 2 digits: approximately 60 valid values across the 3 ranges. Last 4 digits: 10,000 combinations (0000-9999). Total: 100 x 60 x 10,000 = 60 million. With approximately 5.5 million issued since 1996, the system has capacity for decades of continued issuance.

Will the IRS ever change the ITIN numbering format?

There is no indication the IRS plans to change the ITIN format. The current 9XX-XX-XXXX system has sufficient capacity. The IRS could open additional middle digit ranges (66-69, 89, or expand beyond current ranges) if more numbers are needed. Any format change would require updating IRS systems, financial institution databases, and tax software nationwide, making it unlikely without necessity.

Can an ITIN starting with 9 be mistaken for an SSN?

In theory, no, because SSNs never start with 9. However, data entry errors occur. If an ITIN is entered into a system expecting an SSN, it may be processed incorrectly. Some older systems do not distinguish between ITINs and SSNs. Financial institutions with modern systems automatically flag numbers starting with 9 as ITINs. If your ITIN is incorrectly treated as an SSN, contact the institution to correct their records.

Do other countries use a similar numbering system?

Most countries use different formats for tax identification. Canada's SIN is 9 digits but uses a different structure with a check digit. The UK's UTR is 10 digits. Australia's TFN is 8-9 digits with a check algorithm. India's PAN is 10 alphanumeric characters. No other country uses the 9XX-XX-XXXX format. The US ITIN format mirrors the SSN format intentionally to work in existing tax systems.

What happens if you see a 9-digit number starting with 9 but middle digits are outside valid ranges?

A number starting with 9 but with middle digits outside 50-65, 70-88, and 90-99 is not a valid ITIN. It could be a data entry error, a fabricated number, or a number from a different system. Numbers with middle digits 00-49, 66-69, or 89 in the ITIN format are invalid. If you encounter such a number, verify it with the IRS at 1-800-829-1040. Do not use an invalid format number on tax returns.

Why Does Every ITIN Start With 9?

Updated April 2026

Direct answer: All ITINs start with 9 because the IRS reserved this leading digit exclusively for ITINs. SSNs never start with 9. The middle digits (4th and 5th positions) fall in ranges 50-65, 70-88, or 90-99 and indicate when the ITIN was assigned. This numbering system supports approximately 60 million unique ITINs.

Why Did the IRS Choose 9 as the Leading Digit?

When the IRS created the ITIN system in 1996, it needed numbers that would work in existing tax processing systems built for 9-digit SSNs. The solution: use the same XXX-XX-XXXX format but reserve a leading digit that SSNs would never use. The Social Security Administration had never assigned SSNs starting with 9 and confirmed it would not in the future (post-2011 SSN randomization explicitly excludes 9XX). By starting all ITINs with 9, the IRS created an instant identification rule: any 9-digit number starting with 9 is an ITIN, any number not starting with 9 is an SSN. This works across all IRS databases, bank systems, employer payroll software, and tax preparation tools without requiring system modifications. See our ITIN history guide for more background on the 1996 creation.

What Do the Middle Digits (4th and 5th) Tell You?

The 4th and 5th digits of an ITIN are the most informative positions. They must fall in one of 3 ranges: 50 through 65 (16 values), 70 through 88 (19 values), or 90 through 99 (10 values). That gives approximately 45 valid middle digit values. The IRS assigns these ranges in blocks, with earlier ranges filled first. The middle digits also determine expiration scheduling. The IRS expired ITINs by middle digit groups between 2017 and 2021. Knowing your middle digits tells you whether your ITIN was part of an expiration wave. See our ITIN expiration guide for the complete middle digit expiration schedule.

How Does the ITIN Numbering System Prevent SSN Confusion?

The system uses 2 layers of protection. Layer 1: the leading digit 9 is exclusive to ITINs. No SSN starts with 9. Layer 2: the middle digit ranges (50-65, 70-88, 90-99) further narrow the ITIN space. Even if an SSN somehow started with 9 (it does not), its middle digits would likely fall outside the ITIN ranges. Financial institutions use automated validation: when you enter a taxpayer ID, the system checks the leading digit and middle digits to classify it as SSN or ITIN. This classification determines which forms to issue (W-2/1099 vs 1042-S), what withholding rules apply, and how to report to the IRS. Learn more about the format in our ITIN digit format guide.

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Which Middle Digit Ranges Were Expired and When?

Middle Digits	Expiration Year	Status in 2026
70, 71, 72, 78, 79, 80	2017	Expired (unless renewed)
73, 74, 75, 76, 77, 81-88	2018	Expired (unless renewed)
90, 91, 92, 94, 95, 96, 97, 98, 99	2019-2021	Expired (unless renewed)
50-65	N/A	Active (if used in last 3 years)

Even if your middle digits were not in an expiration wave, your ITIN still expires after 3 consecutive years of non-use on a federal tax return. Renewal reactivates the same number.

How Many Unique ITIN Numbers Can the System Support?

The math works out to approximately 60 million possible ITINs. The first 3 digits (9XX) provide 100 combinations (900 through 999). The middle 2 digits provide about 45 valid values across the 3 ranges (50-65 = 16, 70-88 = 19, 90-99 = 10). The last 4 digits provide 10,000 combinations each (0000-9999). Total: 100 x 45 x 10,000 = 45 million in current ranges. If the IRS opens additional middle digit values (66-69, 89, or new ranges), capacity increases further. With approximately 5.5 million ITINs issued since 1996 and about 200,000 to 400,000 new ITINs assigned annually, the current system has capacity for over 100 years at current rates.

Can Financial Systems Automatically Detect an ITIN?

Yes. Modern financial software automatically identifies ITINs using two validation rules: first digit equals 9, and middle digits fall in valid ranges. Banks, brokerages, and payroll systems use this to apply correct tax treatment. For ITIN holders: withholding follows non-resident rules by default, Form 1042-S is issued instead of W-2 for certain payments, and ITIN-specific account policies apply. Some older systems do not distinguish ITINs from SSNs, which can cause issues with credit reporting, account verification, or benefit eligibility checks. If your ITIN is misidentified as an SSN, contact the institution to update their records. See our ITIN vs SSN comparison for all practical differences.

Government Sources

ITIN numbering format per IRS Publication 1915. SSN exclusion of 9XX per SSA POMS RM 10205.001. Middle digit expiration schedule per IRS Notice 2016-48 and subsequent notices. ITIN program statistics from IRS ITIN Program data. Information current as of April 2026.

ITIN Numbering: Frequently Asked Questions

The IRS designated 9 as the leading digit for all ITINs to prevent overlap with Social Security Numbers. SSNs never start with 9 (the SSA excluded 9XX from its numbering system). This ensures instant identification: any 9-digit number in XXX-XX-XXXX format starting with 9 and having valid middle digits is an ITIN. Financial institutions, employers, and IRS systems use this rule to distinguish ITINs from SSNs automatically.

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