In cases where you agree with the change the IRS proposes to your tax account, no reply is necessary unless a payment is due. If you owe additional tax, follow the notice instructions about where to send the extra cash.

When you disagree
If, however, you believe the IRS is wrong, let the agency know as soon as possible. Call the number on the notice, or, if you prefer, send the tax agency a written explanation for the suspected discrepancy.

If you write, feel free to include any documents and information you want the IRS to consider -- such as copies of your tax return, canceled checks or other records -- along with the bottom tear-off portion of the notice. Mail the information to the IRS address shown in the upper left-hand corner of the notice. It generally takes the IRS at least 30 days to get back to you.

Sometimes, the IRS will send a second letter or notice requesting more information or responding to your questions about the original notice. Again, stay calm. These follow-up letters aren't unusual either, just part of the precise tax-resolution process the IRS uses. Simply follow the instructions or answer the additional questions.

Seeking further help
If you find your communications with the IRS about a notice don't end to your satisfaction, you still have options. You can request an appeal under the Collection Appeals Program or you may be entitled to an appeals hearing. Your request must be filed within 30 days of the notice.

You can also ask the Taxpayer Advocate for help in resolving the matter. The Taxpayer Advocate service is an independent system designed to deal with tax problems that are not resolved through normal channels. Each state and IRS service center has at least one local Taxpayer Advocate who independently represents your interests and concerns within the IRS.

The service's main toll-free number is 1-877-777-4778 (or TTY/TTD 1-800-829-4059). If you prefer to speak to an advocate in person, check out IRS Publication 1546, The Taxpayer Advocate Service of the IRS, to find the office nearest you.

Act immediately
Remember, the key to dealing with any IRS notice is prompt action on your part.

If the IRS change to your tax bill is correct, your immediate response to the notice will ensure that you will only owe additional tax and not added penalties and interest. If the IRS is wrong, you definitely want to get the matter corrected as soon as possible to prevent any future tax problems.

And whether you're still working through a notice with the IRS or moving on to the Taxpayer Advocate for help, be sure to keep copies of all IRS correspondence with your tax records.

For more information about IRS notices and tax bills, see Publication 594, Understanding the Collection Process. Information about penalties and interest charges is available in Publication 17, Your Federal Income Tax.

Freelance writer Kay Bell writes Bankrate's tax stories from her Austin, Texas, home. She also writes two tax blogs, Bankrate's Eye on the IRS, and Don't Mess With Taxes.