Overview

Taxpayer Identification Numbers (TINs) are the identifiers the IRS uses to match taxpayers to tax returns, payments, and information returns. Common TINs are the Social Security Number (SSN) for individuals, the Employer Identification Number (EIN) for businesses and certain trusts, and the Individual Taxpayer Identification Number (ITIN) for noncitizens who must file U.S. taxes. Correct TINs matter for withholding, information reporting (Forms W-9, 1099, W-2), and avoiding penalties or backup withholding.

In my 15+ years advising clients, I’ve repeatedly seen small mistakes — using an SSN when an EIN is required, or failing to renew an ITIN — lead to incorrect 1099s, unexpected backup withholding, and extra time dealing with IRS notices. This guide explains when to update a TIN, how to do it, and practical steps to reduce disruption.

Why updating a TIN matters

  • Accurate reporting: Payers use TINs to file 1099s and other information returns. A mismatch between the name and TIN can trigger IRS notices and processing delays (see IRS guidance on TINs and name matching).
  • Avoid backup withholding: If a payer receives an incorrect or missing TIN, they may be required to withhold taxes at the backup withholding rate and send the withheld amount to the IRS (see IRS Form W-9 instructions).
  • Protect personal liability: Using an SSN for business activities can blur legal separateness between personal and business finances.

Authoritative references: IRS — Taxpayer Identification Numbers (TINs) (https://www.irs.gov/businesses/small-businesses-self-employed/taxpayer-identification-numbers-tins), IRS — About Form W-9 (https://www.irs.gov/forms-pubs/about-form-w-9).

When you should update (by situation)

  1. Individual name or status changes
  • Legal name change (marriage, divorce, court order): Notify the Social Security Administration (SSA) to update the name on your SSN record before filing taxable returns under the new name. The IRS uses SSA records to match returns. See SSA form SS-5 and instructions (https://www.ssa.gov).
  • Change in residency/citizenship: If you move from nonresident to resident status (or vice versa), your TIN needs may change (for example, applying for an SSN instead of using an ITIN). See IRS ITIN guidance (Form W-7) (https://www.irs.gov/forms-pubs/about-form-w-7).
  1. Business structure or ownership changes
  1. Starting payroll, opening business bank accounts, or changing tax classification
  • Hiring employees: A sole proprietor with no employees may need a new EIN when they hire employees.
  • Electing new tax classification (e.g., S corporation election): Check IRS rules; sometimes a different EIN is required.
  1. ITIN renewal and expiration
  • ITINs can expire if not used on federal tax returns for a certain period, and the IRS has periodically expired groups of ITINs based on issuance ranges. If your ITIN has expired or will expire, renew it with Form W-7 before filing to avoid processing delays and refund holds. See IRS ITIN information (https://www.irs.gov/individuals/individual-taxpayer-identification-number).

How to update a TIN — step-by-step

This section gives practical steps to update TINs in the most common scenarios. Timely updates reduce the chance of backup withholding and incorrect returns.

  1. Changing an individual’s SSN name or correcting an SSN
  • Update SSA records: File the required documentation with the Social Security Administration (name-change proof, identity documents) to update your SSN record (https://www.ssa.gov/ssnumber/).
  • Provide updated W-9 to payers: After SSA processes the change, give your payers an updated Form W-9 so they can correct their records.
  1. Applying for or updating an EIN
  1. Renewing or applying for an ITIN
  • Submit Form W-7 with required supporting documents or use an IRS Certifying Acceptance Agent (CAA) to avoid mailing originals. Plan for extra processing time during tax season (https://www.irs.gov/forms-pubs/about-form-w-7).
  • If you’ll be filing a tax return, attach the W-7 or renewal request to your return per IRS instructions.
  1. Updating payers and third parties
  • Provide a new Form W-9 (Request for Taxpayer Identification Number and Certification) to any payer who reports payments (clients, platforms, landlords). The payer needs the correct TIN and name to file accurate 1099s (https://www.irs.gov/forms-pubs/about-form-w-9).
  • Check accounts and contracts: Update your TIN with banks, brokerage firms, payroll services, state tax agencies, licensing boards, and other parties that report payments to the IRS.

Timing and practical tips

  • Do it promptly: Update your TIN records as soon as the change happens. There’s no formal “60‑day” IRS window for all TIN changes, but delays increase the likelihood of incorrect reporting and backup withholding.
  • Keep documentation: Keep copies of change requests, confirmation letters from SSA or IRS, and updated W-9s you provided to payers.
  • Use certified professionals when needed: Complex reorganizations and ownership changes often require accountants or tax attorneys to determine whether a new EIN is required.

In my practice, when a client incorporated, we applied for the EIN during formation and updated payroll and bank accounts immediately. That coordination prevented tax reporting mismatches and kept payroll uninterrupted.

Common mistakes to avoid

  • Continuing to use an SSN for business where an EIN is appropriate — this places personal SSNs at greater exposure risk and can complicate tax separation.
  • Waiting to renew an ITIN until after attempting to file — if the ITIN is expired, refunds can be delayed.
  • Forgetting to update third parties — even if you have the correct TIN on file with the IRS, payers must have your updated TIN and name to file correct information returns.

What happens if you don’t update a TIN?

  • Backup withholding: Payers may be required to withhold on reportable payments if you fail to provide a correct TIN (see Form W-9 guidance).
  • Incorrect 1099s/W-2s: Mismatched TIN/name combinations can trigger IRS mismatch notices. Correcting these takes time and may lead to penalties for the payer or taxpayer.
  • Delayed refunds or processing: Especially for ITIN holders and those with recent name or citizenship changes.

Examples

  • Sole proprietor hires employees: The owner should usually apply for an EIN and provide it to payroll and banks to separate personal and business tax reporting.
  • Nonresident who becomes a U.S. resident: They may transition from using an ITIN to an SSN; once they qualify for an SSN, they should obtain one and notify payers and the IRS promptly.

Where to find authoritative procedures and forms

Related FinHelp resources

Final checklist (quick reference)

  • Did your legal name change? Update SSA and then give new W-9s to payers.
  • Did your business structure or ownership change? Determine if you need a new EIN and update payroll/banks.
  • Is your ITIN expired or nearing expiration? File Form W-7 to renew before filing tax returns.
  • Have you sent updated W-9s to all payers and vendors? Keep copies.

Professional disclaimer: This article is educational and does not substitute for personalized tax advice. For complex situations—business reorganizations, international tax status changes, or disputes with the IRS—consult a qualified CPA, tax attorney, or the IRS directly.