Interest paid to the IRS is not tax deductible for individuals. Internal Revenue Code Section 163(h) treats it as personal interest, and personal interest gets no deduction on a federal return.1Office of the Law Revision Counsel. 26 USC 163 – Interest A few narrow exceptions exist for C corporations, for certain non-income business taxes, and for one specific estate tax deferral, but most taxpayers who pay the IRS interest get no tax benefit from it.
Why Individuals Can’t Deduct It
Section 163(h) bars individuals from deducting personal interest, and interest on unpaid federal income tax falls squarely inside that category. It doesn’t matter where the underlying income came from. If the tax deficiency traces back to a sole proprietorship, a rental property, or investment income, the interest on that deficiency is still tied to your personal income tax obligation, and the IRS and courts treat it accordingly.
This catches people off guard after an audit. If the IRS adjusts your income upward and bills you for additional tax plus interest, that interest is a personal cost you absorb with no offsetting deduction. The same rule applies while you’re on an installment agreement. Setting up payments makes the balance easier to manage, but it does nothing to change the tax treatment of the interest itself.
Estimated Tax Underpayment Charges
If you don’t pay enough estimated tax during the year, the IRS imposes a charge under Section 6654. The statute calls it an “addition to the tax,” and it’s calculated using the same underpayment rate that applies to late-paid balances.2Office of the Law Revision Counsel. 26 USC 6654 – Failure by Individual To Pay Estimated Income Tax It functions like interest, but for individual taxpayers it’s not deductible either. Whether the charge is labeled interest, penalty, or addition to tax, the answer is the same.
Interest on Business Taxes Other Than Income Tax
Not every IRS interest charge is personal interest. When a business owes interest on taxes that are separate from income tax, that interest can qualify as an ordinary and necessary business expense. The distinction is the type of tax. Employment taxes like FUTA, certain excise taxes, and other regulatory taxes are costs of running the business, not personal income tax obligations.
A sole proprietor who pays interest on a late FUTA deposit, for instance, can treat that interest as a deductible business expense on Schedule C.3Internal Revenue Service. Instructions for Schedule C (Form 1040) The interest has to be clearly tied to a business tax obligation. If the interest arose from a personal income tax deficiency that happened to involve business income, it goes back to being nondeductible. The test isn’t the source of the income; it’s the type of tax that generated the interest.
C Corporations
C corporations get different treatment because the Section 163(h) personal interest rule applies only to “a taxpayer other than a corporation.” Since a C corporation is a separate taxable entity, interest it pays the IRS on a corporate income tax deficiency is generally deductible as a business expense on Form 1120.
One exception matters. Interest on a tax underpayment that stems from an undisclosed listed transaction or an undisclosed reportable avoidance transaction is not deductible, even for a C corporation.4Internal Revenue Service. Instructions for Form 1120 These are aggressive tax shelters the IRS has flagged. If the corporation participated in one and failed to disclose it, interest on the resulting deficiency loses deductibility. Outside that scenario, the corporate rule is one of the clearest tax advantages of the C corporation form when a dispute produces an interest bill.
Interest on Deferred Estate Taxes
Federal estate tax law lets some estates defer payment rather than paying the full amount at once. Two provisions handle this, and whether the interest is deductible depends entirely on which one applies.
Section 6163 Deferrals: Interest Is Deductible
Section 6163 allows estates to defer tax when the estate includes a reversionary or remainder interest in property. Interest paid on tax deferred under this provision is specifically carved out of the personal interest rule. Section 163(h)(2)(E) says this interest is not treated as personal interest, so it remains deductible. This is a genuinely rare exception to the general rule that interest on federal tax debts produces no deduction.
Section 6166 Deferrals: Interest Is Not Deductible
Section 6166 is the more commonly used deferral, available when a closely held business makes up a significant share of the estate’s value. It lets the estate defer payment for up to five years, then spread the balance over ten annual installments.5eCFR. 26 CFR 20.6166-1 – Election of Alternate Extension of Time for Payment of Estate Tax The point is to keep executors from having to liquidate a family business just to pay the estate tax.
Here’s the trap. Despite the policy behind the deferral, Section 163(k) explicitly prohibits any deduction for interest paid during a Section 6166 deferral period. The estate stretches the payments, but the interest paid over that extended timeline delivers zero tax benefit. Executors handling estates with closely held businesses need to build that nondeductible cost into their cash flow planning from the start.
Penalties Aren’t Deductible Either
People sometimes lump IRS interest and IRS penalties together, and for deductibility purposes that instinct is right: neither is deductible for individuals. Federal law prohibits deducting fines or penalties paid to the government for violating any law, tax law included.6eCFR. 26 CFR 1.162-21 – Denial of Deduction for Certain Fines, Penalties, and Other Amounts Late-filing penalties, accuracy-related penalties, and fraud penalties all fall into this category. Whatever the IRS labels the charge, individuals get no deduction. The only real way to limit the damage is to resolve the underlying balance quickly so the charges stop growing.
State and Local Tax Interest
Interest on unpaid state or local income taxes follows the same rule for individuals: nondeductible personal interest. State and local taxes themselves can be deducted on Schedule A up to the $10,000 SALT cap, but the interest charged on those taxes does not qualify. Corporations can generally deduct interest on state tax deficiencies as a business expense, mirroring the federal treatment of C corporation interest.
When the IRS Pays You Interest
The rule runs in only one direction. When the IRS owes you money and pays interest on a delayed refund, that interest is taxable income. The IRS reports it on Form 1099-INT if the amount is large enough to trigger reporting.7Internal Revenue Service. Topic No. 403 – Interest Received You include it in gross income for the year you receive it, even if the underlying refund itself wasn’t taxable.
That creates an asymmetry worth knowing about. Interest you pay the IRS gives you no deduction, but interest the IRS pays you is fully taxable. If you get a refund with interest attached, watch for the 1099-INT so you don’t underreport and end up paying interest on the interest.