Individual Taxpayer Identification Number

Individual Taxpayer Identification Number. An IRS-issued tax ID for individuals who need a US tax number but cannot get a Social Security Number.

You will encounter the term Individual Taxpayer Identification Number most often in these business situations:

• At formation: Many of these concepts apply when you first create your business entity. Understanding them up front prevents mistakes that are expensive to fix later.
• Annual compliance: Concepts like Individual Taxpayer Identification Number often factor into yearly state filings, tax returns, and federal reports.
• Major transactions: Mergers, acquisitions, fundraising rounds, and significant contracts all involve precise legal vocabulary.
• Disputes and audits: When something goes wrong, the exact meaning of terms matters in court or with the IRS.

• Treating it casually. Business terminology has specific legal and tax meanings. Confusing terms like "trademark" and "copyright" or "shareholder" and "member" leads to expensive mistakes.
• Assuming uniform rules. State law varies significantly. Federal tax rules vary based on entity type. Always verify specific rules for your situation.
• Skipping documentation. Concepts that seem clear today need to be documented to hold up later. Operating agreements, contracts, and minutes formalize understanding.

This entry is part of the File.Business glossary, a reference of 326 business formation and operations terms. Browse all terms or explore the full resource library.