The CP 14 shows the underpaid tax according to IRS records. The notice shows the tax reported on the return, the payments the IRS applied to your account, and the remaining underpayment they have calculated.
Generally, this is caused by a misapplied or missing payment. Check the payments as outlined on the notice the IRS has applied to your account and compare them to your records. If the IRS has missed a payment you made, you will need to provide information to document the payment so they can locate the payment and properly credit your account.
Additional interest and penalties may accrue if the balance is not paid in full by the due date. If you do not agree with the additional tax due, a response should be made to the IRS as soon as possible to settle the issue with your account.
Sections of the Notice:
Header Section This area contains the Notice Number, the applicable tax year, the notice date, your Social Security Number and the IRS contact number and address.
Explanation Section Generally a table that will show the tax due per return, the IRS payments credited to your account, and the balance due (including interest and penalties) calculated based on the IRS records.
Response Section If the payments shown in your records agree with the amounts listed on the CP 14, you should pay the total amount due by the date shown on the notice to avoid additional penalties and interest. This payment should be made using the coupon attached and the envelope provided. If you can't pay the amount due, you may be able to request an installment agreement. If you disagree with the IRS records you will need to contact the IRS at the number or address on the notice to provide the documentation to support your position. The method of contact will be dictated by the information you need to provide the IRS to document the payments made.
Penalties Section This section provides a break-down of the types and amounts of interest and/or penalties being assessed on your balance due.