Most IRS letters and notices are about federal tax returns or tax accounts. Each notice deals with a specific issue and includes specific instructions on what to do. A notice may reference changes to a taxpayer’s account, taxes owed, a payment request or a specific issue on a tax return. Taking timely action could minimize additional interest and penalty charges https://www.irs.gov/payments/penalties.

Including making a payment. The IRS and authorized private debt collection agencies do send letters by mail. Most of the time, all the taxpayer needs to do is read the letter carefully and take the appropriate action or submit a payment
https://www.irs.gov/payments.

If a letter is about a changed or corrected tax return, the taxpayer should review the information and compare it with the original return. If the taxpayer agrees, they should make notes about the corrections on their personal copy of the tax return and keep it for their records. Typically, a taxpayer will only need to take action or contact the IRS if they don’t agree with the information, if the IRS requested additional information, or if they have a balance due.

Taxpayers don’t need to reply to a notice unless specifically told to do so. There is usually no need to call the IRS. If a taxpayer does need to call the IRS, they should use the number in the upper right-hand corner of the notice and have a copy of their tax return and letter.