Back taxes are taxes that were not fully paid by the original due date, typically from a previous tax year. They arise when a taxpayer fails to file a tax return, underreports income, or does not pay the full amount owed by the deadline
. Back taxes can be owed at the federal, state, and local government levels. Unpaid back taxes accrue interest and penalties over time, increasing the total amount owed. Penalties can be significant, starting at 0.5% of the unpaid taxes per month and potentially reaching up to 25% of the tax owed, plus interest which varies quarterly
. The IRS may send notices demanding payment and expects a response within 30–60 days
. If back taxes remain unpaid, serious consequences can follow, including tax liens (legal claims against property), wage garnishment, seizure of assets, withholding of tax refunds, and in severe cases, criminal charges or imprisonment
. Taxpayers with back taxes are encouraged to file past-due returns promptly and may be able to negotiate payment plans or settlements with the IRS, such as an offer in compromise for reduced payment if they cannot pay the full amount
. In summary, back taxes are overdue taxes from prior years that must be paid with added interest and penalties, and failure to resolve them can lead to escalating financial and legal consequences
