A Form 4549 is used by the IRS to report their findings to you upon completion of an examination of your tax return (probably a Form 1040). The IRS will list the changes they propose to make ,and whether these proposed changes will result in additional tax owe by your or an overpayment of tax by you (amount to be refunded).
You should look at what the IRS proposes to change on your tax return.
1. If you agree that they are correct, you should sign the Form 4549 and return in to the address they said in a letter accompanying the Form 4549
2. If you do not agree that they are correct, you must write them and say that you do not agree and explain what you think is correct and why. That must be done within the time specified in the letter accompanying the For 4549.
3. If you do not understand the changes they have proposed, you may either
3a. You may call the phone number shown in the accompanying letter and ask the IRS for a further explanation of the changes, or
3b. You may write them and ask for additional explanation of the changes and additional time in which to consider those changes
But I suggest you contact TT Audit Support at the link in the comment I gave you above.
