If you paid the full amount of your taxes, there would not be additional charges. If the IRS has changed your return, then there could be additional penalties and interest.
You should go ahead and file this year's return. The IRS works on the years separately.
The number for IRS payments is 800-316-6541.
The letter you received, may have a phone number to the IRS office that sent it. That would be the best method of contact.
The general number for the IRS is 800-829-1040 and you want to push as few buttons as possible to get a human. Don't enter your social.
@StarDaweide
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