Form W-9 & 24% Backup Withholding Calculator

Calculate mandatory 24% tax withholding when a contractor is missing a W-9 TIN and print your compliance packet.

24% From Dollar OneApplies to any reportable payment when a signed W-9 is missing.

Gross-Up vs. DeductCompare withholding from the check vs. paying the tax yourself.

CP2100 B-Notice ReadyPrints First & Second B-Notice letters for IRS Form 945 audits.

Vendor Payment Hold, Missing W-9 & IRS Penalty Exposure Inputs

Payer Company Name

Vendor / Subcontractor Name

Pending Invoice / Check Amount ($)

W-9 / IRS CP2100 Notice Status

Total Unfiled / Missing-TIN 1099s in Audit Batch

IRS § 6721 / § 6722 Filing Tier (2026 Penalty Rates)

Generates formal Vendor Payment Hold & IRC § 3406 Notice PDF

IRC § 3406 Check Release vs. Backup Withholding Math

Gross Pending Vendor Invoice	$4,500
Mandatory 24% Backup Withholding (Form 945)	-$1,080
Net Check Payable If Released Without Signed W-9	$3,420

Combined IRS + Payee Penalty Per Return	$660
Batch Penalty Across Missing-W-9 Vendors	$3,300
Total Payer Audit Exposure (Withholding + Penalties)	$4,380