The self employed have to pay both the employer and employee share of FICA (social security & Medicare) tax. This is known as self employment tax (SET) and is in addition to income tax.
SET is only a federal tax. There is no state SET. SET is not a "business tax". It is only how the self employed go about paying FICA, since there is no employer to withhold it from your earned income (wages).
For state income tax, the self employed pay at the same income tax rates as wage earners and other state tax filers.
Residents of Indiana are taxed at a flat state income rate of 3.23%. That means no matter how much you make, you're taxed at the same rate. All counties in Indiana impose their own local income tax rates in addition to the state rate that everyone must pay. Indiana counties' local tax rates range from 0.50% to 2.90%.
For a list of county rates, see https://smartasset.com/taxes/indiana-paycheck-calculator#:~:text=Residents%20of%20Indiana%20are%20ta....
