Lock-In Letters

Letter 2800C and Letter 2801C, mailed to the employer and the taxpayer, respectively, are commonly known as the "lock-in letters" . Letter 2800C instructs the employer to disregard Form W-4 submitted by the taxpayer and withhold at the filing status and withholding rate determined by the IRS. Letter 2801-C advises the taxpayer that the employer has been instructed to disregard Form W-4 submitted by the taxpayer and withhold at the withholding status (filing status) and rate specified in Letter 2800C, unless the Form W-4 results in more tax withheld than the lock-in letter.

Letter 2801C is mailed to the taxpayer's last known address as defined by Treas. Reg. Sec. 301.6212-2. As a general rule, the last known address is the address that appears on the taxpayer's most recently filed tax return or as updated by the National Change of Address (NCOA) database. For further guidance regarding the definition of the last known address see Rev. Proc. 2010-16, 2010-19 IRB.

If the taxpayer's name and social security number (SSN) do not match, always use the Master File address (including reverse validity) belonging to the case SSN.

If the last known address cannot be determined (there is no entity on Master File), the IRS may use the address on the most current Form W-2 for mailing the lock-in letter to the taxpayer. If each Form W-2 shows a different address, use the address on the one showing the most wages. DO NOT update the taxpayer's address of record on Master File, but add the address information to the AMS history and to WHCS.

Letter 2800C and Letter 2801C are mailed at the same time.

Letter 2801C instructs the taxpayer to respond to us within 30 days if the taxpayer wishes to request a modification.

Letter 2800C instructs the employer to lock-in the employee starting with the first pay period ending on or after 60 days from the date of the letter. This ensures that the taxpayer has ample time to respond to the proposed lock-in.