How the bill is built
Indiana calculates property tax in a very different way from most states. Start with your home's gross assessed value (AV), subtract the $48,000 Homestead Standard Deduction, then subtract 40% of what's left as the Supplemental Homestead Deduction. What remains is your net AV, and that is multiplied by your tax district's combined rate (per $100 AV). The result is then capped at 1% of your gross AV under Indiana's circuit breaker — meaning most homesteads in high-rate districts effectively pay 1% flat.
2026 Sullivan County rate breakdown (per $100 AV, Sullivan district)
| Taxing entity | Rate |
|---|---|
| Sullivan City combined rate (per $100 AV) | 4.3256 |
| Combined total | 4.3256 |
As of April 25, 2026 · From Sullivan County Assessor.
Deductions and credits for 2026
Homestead Standard + Supplemental Deductions
Indiana's two-part homestead deduction is the single most valuable tax reduction available to homeowners. For 2026, the Standard Deduction is $48,000 off your gross AV, and the Supplemental Deduction is 40% of what remains after the Standard is applied. Together these typically shield about 65% of a typical home's AV from taxation before any rate is even applied.
File Form HC10 (Homestead Property Tax Deduction) with the Sullivan County Assessor by December 31 of the year preceding the tax year. Many closings handle this automatically — verify on your next tax bill that "Homestead Standard Deduction" appears as a line item.
The 1% Circuit Breaker Cap
Indiana's constitution caps homestead property tax at 1% of gross assessed value. If your calculated tax would exceed that amount (which is common in high-rate districts like Hammond, Gary, and South Bend), the bill is reduced to the cap. Non-homestead residential property is capped at 2%, and commercial at 3%.
Supplemental Homestead Credit (new in 2026)
Under SEA 1, qualifying homesteads receive a credit equal to the lesser of 10% of your tax liability or $300. This is applied automatically to your bill — no application needed.
Over 65 Credit
Replacing the old Over 65 Deduction, this new credit provides up to $150 directly off your tax bill. Income limit is $60,000 single / $70,000 joint. File Form 43708 with your county auditor by January 15 of the tax year.
100% Disabled Veteran Exemption
Veterans with a 100% service-connected disability qualify for a full exemption on their primary residence. Partial disability deductions vary by rating.
Appealing your assessment
If you believe Sullivan-area assessed values on your property are too high, you can file Form 130 (Taxpayer's Notice to Initiate an Appeal) with your township assessor within 45 days of receiving your Form 11 assessment notice, which typically arrives in the spring. Most appeals are resolved informally with the assessor; unresolved disputes go to the county Property Tax Assessment Board of Appeals (PTABOA).