Side Hustle Taxes in Illinois: What to Know

The Flat 4.95%: Simple in Theory

On paper, Illinois has one of the simplest state income tax structures in the country. A flat rate of 4.95% on all taxable income. No brackets to calculate. No phase-outs to track. No marginal rate surprises when your income crosses a threshold. You earn money, you pay 4.95% to the state. Done.

That simplicity is real — and if you're a side hustler living in, say, Champaign or Rockford or Peoria, the simplicity extends to your whole state tax picture. You pay federal taxes on your side hustle income, you pay Illinois 4.95%, and you move on. It's cleaner than California's ten brackets, cheaper than New York's combined state-and-city burden, and only moderately more than Indiana's 3.05% next door.

But about 2.7 million people in Illinois live in Chicago. And another 2.4 million live in the rest of Cook County. For those 5 million people, the flat 4.95% state income tax is the simplest part of a much more tangled tax picture. Chicago layers on its own set of business taxes, license requirements, and peculiarities that can catch side hustlers off guard. Cook County adds its own complications on sales tax. And the combined sales tax rate in some parts of Chicago hits 10.25% — one of the highest in the nation.

So the story of Illinois side hustle taxes is really two stories. One is straightforward. The other involves a spreadsheet.

How Illinois Income Tax Stacks on Side Hustle Earnings

The flat rate makes the state income tax calculation dead simple. Your net side hustle profit on Schedule C gets reported on your federal return. Illinois starts with your federal adjusted gross income, makes a few modifications (most of which don't affect typical side hustlers), and applies 4.95%.

On $30,000 of net side hustle income, Illinois takes $1,485. That's it. No stacking on top of W-2 income to worry about — because it's a flat rate, the answer is the same whether your side hustle is your only income or whether it sits on top of a $200,000 salary. $30,000 times 4.95% equals $1,485 regardless.

Compare that to California, where the same $30,000 might be taxed at 9.3% ($2,790) if you have a day job pushing you into the upper brackets. Or New York, where the state takes 6.25% ($1,875) plus NYC adds another $1,163. Illinois's $1,485 is competitive — not free like Texas or Florida, but not devastating either.

The full federal-plus-state picture on $30,000 of side hustle income for an Illinois resident in the 22% federal bracket:

Federal income tax: ~$6,600. Self-employment tax: ~$4,238. Illinois income tax: $1,485. Total: approximately $12,323. You keep $17,677 out of $30,000. The effective combined rate is about 41% — higher than the 36% you'd pay in Texas or Florida, but lower than the 45-48% you'd face in New York City or the 43-44% in California.

One thing Illinois does that's favorable to side hustlers: the state does not tax retirement income, and it provides a full exemption for federally tax-exempt income. Neither of these directly affects current side hustle income, but if you're using side hustle earnings to fund a Solo 401(k) or SEP-IRA, the contributions reduce your federal AGI, which in turn reduces your Illinois taxable income. The flat rate means the deduction is worth exactly 4.95% of whatever you contribute — predictable and easy to calculate.

Illinois Estimated Tax Payments

Illinois requires estimated tax payments if you expect to owe more than $500 in state income tax after subtracting withholding and credits. On side hustle income, you'll cross this threshold at roughly $10,000 in net profit — so most side hustlers earning anything meaningful will need to make quarterly payments.

Use Form IL-1040-ES. Quarterly due dates follow the federal schedule: April 15, June 15, September 15, January 15. You can pay electronically through the Illinois Department of Revenue's MyTax Illinois portal.

The safe harbor works the same way as federal: pay at least 100% of last year's Illinois tax liability in four equal installments, and you won't face an underpayment penalty regardless of what you owe this year.

If you have a W-2 job in Illinois, the simpler approach is increasing your state withholding. File a new IL-W-4 with your employer and request additional withholding. Estimate your side hustle state tax ($30,000 net x 4.95% = $1,485), divide by pay periods (26 if biweekly = $57.12 per paycheck), and you're done. No quarterly forms, no separate payment dates.

Chicago's Business Tax Maze

Chicago doesn't have a city income tax. That's the good news. Illinois law actually prohibits municipalities from levying their own income taxes (unlike Ohio, where dozens of cities have income taxes). So there's no additional income tax layer for Chicago side hustlers on top of the state's 4.95%.

The less good news: Chicago finds other ways to tax business activity, and some of them apply to side hustlers in ways that aren't immediately obvious.

The Personal Property Lease Transaction Tax. This applies when you lease or rent tangible personal property in Chicago. The rate is currently 9% of the lease or rental price. Most side hustlers aren't leasing equipment to others, so this tax is irrelevant. But if your side hustle involves renting out equipment, tools, party supplies, or similar items within Chicago, this tax applies and it's steep. Notably, this tax was also applied to cloud computing services (leasing access to software or infrastructure), though legal challenges and legislative changes have created some ambiguity around its scope.

The Amusement Tax. Chicago levies a 9% Amusement Tax on charges for the privilege of witnessing, viewing, or participating in amusements in Chicago. This has been extended to streaming services — Chicago charges the tax on streaming video, streaming music, and online games. For most side hustlers, you're paying this tax as a consumer, not collecting it. But if your side hustle involves hosting events, providing entertainment, or operating any kind of amusement within Chicago, you may need to collect and remit this tax.

Business registration. Most businesses operating in Chicago need a City of Chicago Business License. The requirements depend on your business type. Some home-based businesses are exempt from certain license requirements, but if you're selling goods, providing services at a commercial location, or operating any kind of storefront (even pop-up), check the City's Business Affairs and Consumer Protection department for your specific licensing requirements.

None of these individually are as burdensome as, say, California's $800 LLC franchise tax or New York's UBT. But the patchwork nature — a tax here, a license there, a registration requirement you didn't know about — creates a cumulative administrative burden that the flat 4.95% state income tax doesn't hint at.

Cook County Complications

Cook County — which includes Chicago and about 130 surrounding municipalities — has its own layer of tax complexity, particularly around sales tax.

The combined sales tax rate in Chicago is 10.25%, which stacks like this: 6.25% Illinois state + 1.75% City of Chicago + 1.0% Cook County + 1.25% Regional Transportation Authority. Outside Chicago but within Cook County, the rate is slightly lower — typically 9% to 10% depending on the municipality.

For side hustlers selling physical products, this affects both your pricing and your compliance obligations. If you sell at craft fairs in Chicago, you're collecting 10.25% sales tax. Drive 45 minutes to a craft fair in DuPage County and you might be collecting 7.5-8%. Different jurisdictions, different rates, different remittance requirements. The Illinois Department of Revenue handles the state portion uniformly, but you need to know the correct combined rate for each location where you make sales.

Cook County also has a sweetened beverage tax that was famously repealed in 2017 after public backlash, but it illustrates the county's tendency to explore creative revenue sources. Currently, Cook County imposes a $0.02/unit tax on cartridge-based e-cigarettes and various other county-level excise taxes. Most side hustlers won't encounter these, but if your side hustle falls into a niche product category, check whether Cook County has a specific tax on it.

The practical advice for Cook County side hustlers: use tax software or a sales tax automation service (TaxJar, Avalara) if you sell physical products across multiple jurisdictions. Trying to manually track rates for Chicago vs. Evanston vs. Schaumburg vs. Naperville is the kind of spreadsheet work that makes people consider moving to Indiana.

Illinois LLC Filing and Annual Costs

Forming an LLC in Illinois costs $150 for the Articles of Organization, filed with the Illinois Secretary of State. You can file online, and the process is straightforward.

The annual cost is a $75 annual report, due each year before the first day of the anniversary month of your LLC's formation. So if you formed your LLC in March, your annual report is due by March 1 each year. Miss the deadline and the state charges a $100 late fee. Continue to miss it and the state can dissolve your LLC.

At $75 per year, Illinois is one of the more affordable states for LLC maintenance. California charges $800 annually. Florida charges $138.75. Texas charges nothing for the filing but requires a franchise tax report. Illinois's $75 is easy to stomach even for a small side hustle.

One quirk: Illinois used to charge $250 for LLC formation and $75 for the annual report. The formation fee was reduced to $150 in 2023. If you see older guides quoting $500 or $250, they're outdated.

For the question of whether you need an LLC at all, the Illinois-specific cost doesn't change the analysis much. $75 per year is cheap enough that the decision should be based on liability protection needs and how you want to manage your business identity, not on trying to save $75.

Sales Tax for Online Sellers in Illinois

Illinois's sales tax structure is more complex than most states because it distinguishes between different types of goods and applies different rates.

General merchandise: 6.25% state rate plus local additions. In Chicago: 10.25% combined. In other parts of the state: typically 6.25% to 9% combined.

Qualifying food, drugs, and medical appliances: Taxed at a reduced 1% state rate (plus applicable local rates). If your side hustle sells food products that qualify under this category, your effective rate is much lower than the general merchandise rate.

Illinois uses origin-based sourcing for in-state sales made by Illinois-based sellers — meaning you charge the sales tax rate for your location, not the buyer's location. If you're based in Chicago (10.25%) and sell to a buyer in Springfield, you charge the Chicago rate. This is different from many states that use destination-based sourcing, and it's important to get right.

However, for remote sales (online orders shipped to buyers), Illinois switches to destination-based sourcing. An Illinois e-commerce seller shipping to a Chicago address charges the Chicago rate; shipping to a Peoria address charges the Peoria rate. This dual-sourcing system is one of the things that makes Illinois sales tax unnecessarily complicated.

Marketplace facilitators (Amazon, Etsy, eBay) collect and remit Illinois sales tax on sales through their platforms. If you sell through your own website, at craft shows, or through other non-marketplace channels, you need to register with the Illinois Department of Revenue and handle collection and remittance yourself.

How Illinois Compares to Indiana and Wisconsin

Illinois sits between two states with very different tax structures, and the comparison matters for side hustlers near the borders — which, given that Chicago's metro area bleeds into Indiana and Milwaukee is 90 miles north, includes a lot of people.

Indiana has a flat state income tax rate of 3.05% — nearly 2 percentage points lower than Illinois. On $30,000 of side hustle income, Indiana takes $915 vs. Illinois's $1,485. That's $570 per year in savings. But Indiana also has county income taxes — every county in Indiana levies its own income tax, typically between 1% and 3% on top of the state rate. In Lake County, Indiana (just across the border from Chicago), the county rate is about 1.59%, bringing the combined rate to 4.64%. Still less than Illinois's 4.95%, but the gap is much smaller than the state-rate comparison suggests.

Indiana also has a lower combined sales tax in most areas (7% flat statewide) compared to Chicago's 10.25%. For side hustlers who sell physical products and live near the Indiana border, this rate difference is material — both for personal purchases and for where you set up your business.

Wisconsin has a graduated income tax with rates from 3.5% to 7.65%. For side hustlers earning less than about $15,000 in net profit, Wisconsin's lower brackets (3.5-4.4%) are cheaper than Illinois's flat 4.95%. Above roughly $30,000, Wisconsin's 5.3% bracket starts to exceed Illinois, and at higher income levels the gap widens significantly — Wisconsin's 7.65% top rate is more than 50% higher than Illinois's flat rate.

Wisconsin's sales tax is 5% state plus county additions of 0-0.5%, making the combined rate 5-5.5% — substantially lower than Illinois, especially compared to Chicago.

The net effect for side hustlers: Indiana is modestly cheaper than Illinois for most income levels, though the county tax narrows the gap. Wisconsin is cheaper at low income levels and more expensive at higher levels. Neither difference is dramatic enough to justify a move on tax grounds alone — we're talking $500-$800 per year in most scenarios. But for someone already living near a border and weighing where to establish their side hustle's legal home, the differences are worth considering.

Bruce Samuels

Personal Finance Writer

Bruce writes about side hustle taxes from DeSoto, Texas. He spent time in the Chicago suburbs before moving south and has a healthy respect for Illinois's ability to complicate a flat tax. He is not a CPA.

Related reading: The Complete Side Hustle Tax Guide | How to Pay Quarterly Estimated Taxes | Do I Need an LLC for My Side Hustle?