The statutory notice of deficiency (also known as a  "stat notice") states the position of the IRS after they have finished examining your income tax return. Generally, unless you reside abroad, you have 90 days from the date of the statutory notice of deficiency to petition the Tax Court to consider your case. This date should be stated at the top of the stat notice you receive. If you do not petition the Tax Court within that 90-day period, the amount of tax stated in the stat notice will be billed to you and you will need to pay upon receipts of that bill, or incur further interest and penalties.