Illinois S-Corp Tax Calculator

Self-employment tax is federal — 15.3% (12.4% Social Security up to the $184,500 wage base + 2.9% Medicare) on 92.35% of your net self-employment income, the same in Illinois as everywhere. Illinois then taxes that same income at its state income-tax rate (up to 4.95%). The calculator above shows your SE tax at any income.

In Illinois, at this calculator's default assumptions, it pays off between $65,897 and $83,475 of net profit, and again between $91,951 and $211,877, and again from $270,714 — above $211,877, the salary is still paying Social Security tax after a sole proprietor's has stopped at the wage base; from $270,714, the QBI wage limit takes the deduction from a sole proprietor with no payroll, and the salary keeps it. Below $270,714 of net profit, it never saves more than about $1,108 a year at these assumptions. That assumes a salary of 60% of net profit (capped at the $184,500 Social Security wage base), $2,500 a year for payroll and the extra business return, a single filer with no other income taking the $16,100 standard deduction, a business that is not a specified service business (not consulting, law, health, financial services and the like) and an LLC you already have, so its annual fee is paid either way. It counts federal payroll tax, federal income tax (including the QBI deduction the salary changes) and what IL charges for the election. Your own state income tax is not in it. A lower defensible salary moves the answer, and so do your own payroll and return quotes.

Illinois charges an S-corp its 1.5% Personal Property Replacement Tax on net income. The owner of a single-member LLC pays none, so all of it is a cost of electing.

Yes. Illinois offers a pass-through entity tax (PTET) election that lets the business pay state income tax and deduct it federally, bypassing the federal SALT cap on that income. The cap is $40,400 for 2026 but phases down toward $10,000 above ~$505,000 of MAGI, so PTET matters most for higher earners. If you elect S-corp, this often stacks on top of the SE-tax savings.

The IRS requires S-corp owner-employees to pay themselves a reasonable salary (subject to FICA) before taking distributions. This calculator assumes a salary of 60% of net profit (capped at the $184,500 Social Security wage base), with the rest taken as distributions, as an illustration — your actual reasonable compensation depends on your role and industry and should be set with a CPA.