You can find the CP or LTR number on the right corner of the letter. Letter 6419 includes: Number of qualifying children used to calculate advance payments, and repayment protection when filing your 2021 federal tax return.Here are some tips on spotting a fake IRS letter and protecting yourself and your business from tax scams. The audit reconsideration request is a filing a taxpayer can make to ask the IRS to reconsider its prior changes to a tax return. Request Certificates of Account Status for Termination or Withdrawal and Tax Clearance Letters for Reinstatement. You can get in-person help at your local IRS Taxpayer Assistance Center. Call for an appointment after you find a Taxpayer Assistance Center near you. The 2800C letter notifies the employer to start making backup withholding. The IRS website has forms for 1975 and onward. Ensure you receive confirmation before assuming the change is complete.