A CP04 notice is sent by the IRS to individuals who have served in a combat zone, a qualified contingency operation, or a hazardous duty station during the tax year specified on the notice. This notice indicates that you or your spouse may be eligible for tax deferment due to this service.

A CP09 notice is sent by the Internal Revenue Service (IRS) to taxpayers who may be eligible for the Earned Income Credit (EIC) but did not claim it on their tax return. The EIC is a credit for certain people who work and have earned income. The credit may give you a refund even if you do not owe any tax.

A CP11 notice is a letter sent by the IRS when they have made changes to your income, deductions, and credits on your tax return. This usually happens when the IRS believes there’s a miscalculation on your tax return. As a result of these changes, you may owe money.

A CP12 notice is a letter sent by the IRS when they have made changes to your income, deductions, and credits on your tax return. This usually happens when the IRS believes there’s a miscalculation on your tax return. As a result of these changes, you may be due a refund.

A CP14 notice is a letter sent by the IRS when they have made changes to your income, deductions, and credits on your tax return. This usually happens when the IRS believes there’s a miscalculation on your tax return. As a result of these changes, you owe money on unpaid taxes.

A CP16 notice is a letter sent by the IRS when they have made changes to your income, deductions, and credits on your tax return. This usually happens when the IRS believes there’s a miscalculation on your tax return. As a result of these changes, you owe money on unpaid taxes.

A CP13 notice is a letter sent by the IRS when they have made changes to your income, deductions, and credits on your tax return. This usually happens when the IRS believes there’s a miscalculation on your tax return. As a result of these changes, you’re not due a refund nor do you owe an additional amount. Your account balance is zero.

A CP21A notice is a letter sent by the IRS when they have made changes to your income, deductions, and credits on your tax return. This usually happens when the IRS believes there’s a miscalculation on your tax return. As a result of these changes, you owe money on unpaid taxes.

A CP21B notice is a letter sent by the IRS when they have made changes to your income, deductions, and credits on your tax return. This usually happens when the IRS believes there’s a miscalculation on your tax return. As a result of these changes, you’re due a refund.

A CP21C notice is a letter sent by the IRS when they have made changes to your income, deductions, and credits on your tax return. This usually happens when the IRS believes there’s a miscalculation on your tax return. As a result of these changes, you’re not due a refund nor do you owe any additional amount. Your account balance for this tax form and tax year is zero.