IRS TIN Matching Service Hello again, This post is about the IRS Taxpayer Identification Number (TIN) Matching Service – we hope you find it useful. This documentation is intended to help you become an authorized user of the IRS TIN Matching Service and learn to use it for your greatest benefit. Steps to sign up … Continue reading IRS Taxpayer Identification Number (TIN) Matching Service (Steps for Sign-up and Usage)