Indiana Sales Tax Penalty and Interest Calculator

How Indiana Sales Tax Penalties and Interest Work

Indiana's sales and use tax is administered by the Indiana Department of Revenue. The agency can charge separate 10 percent penalties for late filing and late payment of sales and use tax, with a minimum of $5.00, and an interest rate set annually under Indiana Code IC 6-8.1-10-1, calculated as two percentage points above the average investment yield on state general fund money.

For 2026, that interest rate is 7 percent per year — approximately 0.58 percent per month. Because penalty and fee charges apply per filing period, a business with delinquent returns across several periods can build a tax liability far larger than the original tax due, which is exactly what this multi-period calculator totals.

Late Filing vs. Late Payment Penalties in Indiana

Indiana charges a 10 percent penalty on the unpaid tax liability — or $5.00, whichever is greater — when a taxpayer fails to file or fails to pay sales and use tax by the due date. A separate penalty applies if a return is prepared by the Indiana Department of Revenue because the taxpayer failed to file; in that case, the penalty rises to 20 percent of the tax due. A fraudulent return or fraudulent intent to evade tax carries a penalty of 100 percent of the tax due. An additional 10 percent penalty applies to payments required to be made electronically that are not. There is no combined penalty cap that merges filing and payment failures into a single charge — each violation carries its own fee. (IC 6-8.1-10-2.1)

Separate assessment penalty: Beyond the standard late penalty, if the Indiana Department of Revenue issues a proposed assessment — such as an audit deficiency — and it becomes final and unpaid, additional interest and enforcement costs continue to accrue. This is not included in the calculator's standard estimate, meaning an audited or state-billed balance can run higher than the figure shown.

Example: If your business owed $25,000 in Indiana sales tax for a period and resolved it many months late, the penalty and fee charges plus accrued interest can add thousands on top of the original tax due — and that is for a single period.

Both the date you file and the date you pay matter. A tax return filed six months late is treated differently from a return filed on time, where only the payment was late.

How Indiana Interest Applies

Indiana charges an interest rate equal to two percentage points above the average investment yield on state general fund money, rounded to the nearest whole number, reviewed annually under IC 6-8.1-10-1. For all of 2026, the rate is 7 percent per year — approximately 0.58 percent per month. Interest accrues on the unpaid tax amount at the annual adjusted rate from the due date, not by month or fraction thereof under state law.

Interest begins the day after the due date and continues to accrue until the full balance is paid, regardless of whether a payment plan is in place. For a deficiency determination arising from an Indiana DOR audit, interest reaches back to the date the tax originally should have been paid — not the date the DOR issued the bill.

Why Sales Tax Debt Is Different From Income Tax Debt

This is the part most business owners underestimate. When you collect Indiana sales tax from a customer, you are holding money that belongs to the state. If that money is not remitted, the Indiana Department of Revenue may treat it as a trust fund tax, not an ordinary tax obligation you simply fell behind on.

That distinction changes what the state can do:

Collected-but-unremitted tax is viewed as the state's money, not yours.

Responsible-person liability can reach owners, officers, partners, members, or employees who controlled the money.

Personal assessments may survive even if the business closes or files for bankruptcy.

Business bank levies, liens, and license suspension can move faster than with income tax debt.

Audit escalation and, in serious cases, criminal referral — under IC 6-2.5-9-3, knowingly failing to collect or remit trust fund tax is a Level 6 felony — can occur where tax was collected and intentionally not paid.

Not every case is criminal — most are not. But serious cases, especially where tax was collected and knowingly kept, can involve criminal exposure. That is why delinquent sales tax debt deserves a careful look early.

Indiana Sales Tax Agency and Enforcement

Indiana's sales and use tax is administered by the Indiana Department of Revenue. Returns and payments must be submitted electronically through the INTIME portal. Notices typically arrive by mail and can range from a balance-due bill to a delinquency notice, an audit notice, a lien filing, a levy on business bank accounts, or a threat to the sales tax permit or business license.

State revenue agencies generally have strong tax collection tools and may pursue responsible persons for trust fund amounts. Payment plans, penalty waiver, and settlement options may exist, but availability depends on the facts and the Indiana DOR's rules. If you have received any notice from the Indiana Department of Revenue, it is best reviewed promptly — sales tax timelines move faster than most business owners expect.

Indiana Sales Tax Audit Assessments

If your balance comes from an Indiana DOR audit assessment, the numbers above may not match the state's figures. Indiana DOR audits can add tax, penalties, fee charges, and interest, and findings often involve underreported sales, denied exempt or resale certificate transactions, missing exemption certificate documentation, marketplace or online sales, or cash-sales reconstructions. A notice of proposed assessment issued after an audit includes the amount due and explains your appeal rights, including the right to file a protest.

Audit assessments also carry appeal and protest deadlines that can be short. Ignoring an audit notice usually makes the outcome worse. If you received an Indiana DOR assessment, the most useful next step is a review before the deadline passes — not a recalculation.

Responsible-Person / Personal Liability

Under Indiana law, owners, officers, partners, members, or other responsible persons may be held personally liable for unpaid sales tax, particularly trust fund tax that was collected from customers. Under IC 6-2.5-9-3, any individual who has a duty to remit gross retail or use taxes holds taxes in trust for the state and is liable for the tax, penalties, and interest; knowingly failing to remit is a Level 6 felony.

Closing the business does not always eliminate the tax obligation or personal exposure.

LLC or corporate protection may not fully shield against a trust-tax assessment.

Who signed returns, controlled the bank accounts, decided which bills got paid, or handled the tax money can all matter.

Rules vary by state, and personal liability depends on the facts.

Because a personal assessment can attach to your own assets, this is worth reviewing early — before the Indiana DOR names a responsible person.

Business Closed With Unpaid Indiana Sales Tax?

A closed business does not automatically erase unpaid tax obligations. The Indiana Department of Revenue can still pursue the entity and, where trust fund tax was collected, may pursue the responsible people behind it. Final returns, unfiled periods, and a past-due balance are common triggers for tax collection action and personal assessment. Under Indiana's successor liability provisions enacted in 2024, acquiring businesses may also inherit unpaid sales tax liabilities unless proper notice and tax clearance procedures are followed. If your business has closed with delinquent sales tax still owed, it is better to understand the exposure than to wait for a notice.

Indiana Penalty Relief, Waiver, and Resolution Options

Depending on the facts, options may include penalty abatement or waiver, a reasonable-cause request, a payment plan, voluntary disclosure (for unregistered or unfiled periods), amended returns, a tax appeals protest, a settlement or offer where the state allows it, a business-hardship request, a responsible-person defense or review, and compliance cleanup for missing returns.

Penalty relief is not automatic. The Indiana DOR will generally look at facts such as your filing history, payment history, the reason for noncompliance, whether tax was collected, whether the business cooperated, and whether you are now compliant. To request relief, taxpayers must make an affirmative showing of all facts alleged as reasonable cause in a written statement filed under penalty of perjury. The statement must be filed with the return or payment within the time prescribed for protesting departmental assessments.

Indiana Sales Tax Payment Plans

Indiana allows an installment agreement for unpaid sales tax, sometimes with conditions — staying current on new returns, a down payment, or financial disclosure. A payment plan can stop or slow some tax collection action, but terms and eligibility depend on the balance, the periods involved, whether returns are filed, and your compliance history. Terms are account-specific and may require financial disclosure. If keeping the business open matters, getting the plan structured the first time correctly is important.

When to get help immediately

Do not rely only on an online calculator if any of these apply to your Indiana sales tax situation:

Tax was collected from customers but not remitted to the Indiana DOR.

The state issued a levy notice, filed or threatened a lien.

The state threatened to suspend your sales tax permit or business license.

The business is under audit, or the Indiana DOR is asking about responsible persons.

The business closed with unpaid sales tax still owed.

Sales tax money was used for payroll, rent, vendors, or other business expenses.

You have received multiple notices, or there is a court date, subpoena, or investigator contact.

Common Indiana Sales Tax Cases We Review

If any of these sound like your situation, a confidential review is worth more than a recalculation:

A restaurant or retailer collected sales tax but used the funds for payroll, rent, or vendors.

A contractor, shop, or seller missed multiple filing periods and failed to file a timely return.

The business closed with unpaid Indiana sales tax still owed.

The Indiana DOR issued a sales tax audit assessment.

An owner or officer received a personal-liability / responsible-person questionnaire.

The sales tax permit or business license was threatened or held.

A bank levy or lien was filed against the business.