Eleven long-form guides covering the whole loop: what the IRS checks, how TIN matching works, the W-9 solicitation schedule, the CP2100 and B-Notice procedure, backup withholding, Notice 972CG, sanctions screening, foreign payees, and a worked example.
The full loop from W-9 to penalty notice, and why TIN matching is one step, not the whole job.
What the IRS compares, what the nine result codes mean, and why a mismatch is not always the vendor's fault.
Initial, first-annual and second-annual solicitations, and the records that prove you made them.
The 15-day and 30-day clocks, when not to send a notice, and the second-notice rule that trips up most payers.
Triggers, deposits, Form 945, and how to stop withholding once a TIN is fixed.
The 2026 per-return amounts, the 45-day response window, and what a reasonable-cause statement has to prove.
OFAC, SAM and the other lists that matter for accounts payable, and how often to re-screen.
Onboarding, quarterly, pre-filing and post-notice tasks on one page.
The root cause of most TIN mismatches, explained for payees and for the AP team that has to fix it.
One notice season at a mid-sized company, from logging the notice to the 972CG eighteen months later, with where the hours went.
How to tell a foreign payee from a U.S. one, which W-8 to collect, 30% chapter 3 withholding and treaty claims, and why a foreign vendor on a CP2100 is a filing error.
Looking for a number or a date? See the 2026 figures and the compliance calendar. Not sure which notice you have? Try the notice decoder.