B-notices (CP2100) arrive when the name and TIN on a 1099 don’t match IRS records. The good news: they’re almost entirely preventable with bulk TIN matching before you file. 1099Express offers bulk TIN matching for $74 per file, or interactive matching at $1 per recipient — both processed directly through the IRS database.
Best practice: run TIN matching in November or early December so you have time to collect corrected W-9s before the January filing deadline.