Most guides to starting a law firm end up telling you to check with your state bar.
It’s reasonable advice. The requirements genuinely vary, and a national publisher can’t know what Illinois asks for. But it means that at the exact point you need an answer, the article stops.
This is the Illinois answer. ARDC registration and what it costs, why you need a PLLC rather than an LLC, how the trust account works, what the ARDC does with your address, the Cook County attorney number, and what the whole thing adds up to.
Where there’s an argument to be had rather than a fact to state — whether you need an office, what software to buy, where your first clients come from — I’ve linked to a longer piece rather than compressing it here.
In full disclosure: I run a company that rents offices and provides support staff to attorneys. The compliance figures below aren’t mine to shade and I’ve sourced them.
What do you need to start a law practice in Illinois?
Two things, and one of them may be free: ARDC registration, and a client trust account if you’ll hold client money. That’s the genuine floor. Mandatory cost is $385 a year, or nothing at all if you were admitted since January 2025.
Everything else on any startup list — including forming an entity — is a choice.
That surprises people, and it surprised me when I worked through it properly. Illinois does not require you to register a sole proprietorship, so an attorney can hang a shingle without filing anything with the Secretary of State. You’d register an Assumed Name only if you practise under a name other than your own.
The sequence that avoids rework, if you do form an entity: file it, get the EIN, open the accounts, register with the ARDC, then get your Cook County attorney number before you need to file anything.
Do you need a business plan?
Only if you’re borrowing money. If you’re funding it yourself, you need four numbers: what you’ll bill, what you’ll collect and when, what it costs to run, and how long you can go without income. A twenty-page plan is a document written to persuade a lender. The exercise that matters is finding out whether the arithmetic closes.
The fourth number — your runway — is the one that decides whether the practice survives, and nearly every template mentions it in a single line.
What entity should an Illinois law firm be?
If you form one at all, a PLLC — not a standard LLC. Illinois has required licensed professionals to use a professional limited liability company since August 2018, and existing LLCs had to amend. You are not obliged to form anything; a sole proprietorship requires no state filing.
The filing chain:
| Step | Cost |
|---|---|
| Articles of Organization, Form LLC-5.5, Secretary of State | $150 |
| Certificate of Registration, IDFPR | $50 |
| Annual report, Form LLC-50.1 | $75/year |
| EIN from the IRS | Free |
The entity question has its own piece — the full detail is here, including why you’d form one despite not having to.
If you form an entity you need a registered agent with a physical Illinois street address — a PO box won’t do. You can serve as your own if you’re an Illinois resident with a street address, though your name and address then become public record. A commercial service runs roughly $50 to $200 a year.
A sole proprietor needs none of this. No filing, no registered agent, no annual report.
Why form one anyway
Because as a sole proprietor you are personally liable for every contract you sign. The office lease, the equipment agreement, the vendor contract, the staffing arrangement — if the practice can’t pay, the claim is against you and your assets. There is no separation, because there is no second entity. You and the firm are the same legal person.
Sign a three-year office lease as a sole proprietor and close the practice in year two, and the landlord’s claim is against you personally. Sign it through a PLLC and the claim is against the PLLC.
That’s what $200 and a $75 annual report buys, and for most attorneys it’s the easiest decision on this page.
One thing it does not buy, and this matters: a PLLC does not shield you from your own malpractice. You remain personally liable for your own professional negligence whatever entity you practise through. That’s what the insurance is for, and it’s why the two are separate decisions rather than alternatives.
In full disclosure, Amata leases offices to attorneys, so I’m on the other side of exactly the contract I’m describing. I’d still rather you signed ours as a PLLC.
What does ARDC registration cost?
$385 a year if you were admitted before January 1, 2025, and nothing at all if you were admitted since then. The reduced $121 early-career fee for attorneys under three years’ admission was eliminated effective October 2024, so there is no longer an intermediate rate between free and the full amount.
The address you give the ARDC goes on the public master roll. So does the address on your appearance and your pleadings. Both are visible to every opposing party and every client in every matter you handle.
That’s the practical reason attorneys use something other than their home, and it’s worth deciding before you register rather than after.
Do you need a physical office in Illinois?
No. Illinois has no rule requiring a brick-and-mortar office, and ABA Formal Opinion 498 confirms a practice may be entirely virtual. What you need is a business address that isn’t your house, and — depending on practice area — somewhere to meet clients.
The longer version separates four questions people collapse into one: whether you need an office, whether you need an address, whether you need a meeting room, and whether you should work alone. The fourth is the one nobody writes about.
How does the trust account work?
Client funds go into an interest-bearing client trust account at an ARDC-eligible institution. Illinois prohibits non-interest-bearing trust accounts, and short-term or nominal funds go into a pooled IOLTA account with interest remitted to the Lawyers Trust Fund of Illinois. Rules 1.15, 1.15A and 1.15B govern it.
What the rules actually require of you: monthly three-way reconciliation, a separate ledger for each client matter, and seven-year record retention.
That’s the compliance task most likely to cause a new solo real trouble, and it isn’t something to learn on live client funds. Most attorneys use either legal-specific accounting software or a bookkeeper who understands trust accounting. Some use both.
You’ll also want three accounts, not one: an operating account, a savings account for taxes, and the IOLTA. Keeping them separate is not optional.
Do you need malpractice insurance?
No, Illinois doesn’t require it. What Rule 756(e) requires is that you disclose annually whether you carry coverage — and if you’re in private practice without it, you must complete the ARDC’s four-hour Proactive Management-Based Regulation self-assessment every two years.
Not insurance. Homework, plus a public record of your answer.
Carry it anyway. A first-year policy typically runs under $1,000, because claims-made coverage has almost no prior work to insure. It steps up each renewal to around $2,000–$4,000 by year five or six.
ISBA Mutual reports the average cost of defending a meritless claim at about $28,000. A claim doesn’t need merit to be filed against you.
What software do you actually need?
Less than you’d think, and in Illinois considerably less — because ISBA membership includes vLex Fastcase, which sells standalone at $695 a year, and membership is free in your first year after admission. A working stack runs about $1,400 annually. A minimum one can run under $100.
Only two practice areas genuinely require specialist software: immigration and bankruptcy. Probate sits just below. The other five run fine on general practice management.
What do you need for Cook County?
A five-digit Cook County Attorney Number, which is separate from your ARDC number, obtained from the Clerk of the Circuit Court. You need it before you can e-file anything, and attorneys leaving a firm must get their own rather than using the former firm’s.
E-filing itself is free. Illinois mandates e-filing in civil cases through Odyssey eFileIL, which charges no service fee — though statutory court filing fees and payment processing still apply. Paid filing services exist and are optional.
Recording with the Cook County Clerk’s Recordings Division is a flat $107 for most document classes regardless of page count.
Where do your first clients come from?
People who already know your work — former colleagues, opposing counsel, past clients, and attorneys in adjacent practice areas who get calls they can’t take. Almost never from a website in the first six months, regardless of how good the website turns out to be.
The highest-return hour of the entire launch is an email telling people you’ve started. Attorneys routinely delay it for weeks while building a website, and it costs them a quarter.
Who to tell, what to say, and when marketing starts to matter →
What does the whole thing cost?
Between roughly $1,200 and $23,400 in year one, depending almost entirely on whether you have clients when you start. A newly admitted attorney working from home with a business address is at the bottom. An experienced attorney with an office and support is at the top.
Neither figure includes operating capital or health insurance, and the first of those is larger than everything else combined.
Frequently asked questions
The only mandatory cost is ARDC registration — $385 annually, or nothing if admitted since January 2025. Illinois does not require entity formation, so a sole proprietorship adds nothing. A PLLC costs $150 plus $50 IDFPR and $75 yearly. Realistic first-year totals run $1,200 to $23,400.
A PLLC. Illinois has required licensed professionals to use a professional limited liability company since August 2018, and existing LLCs were required to amend. Generic Illinois LLC guides, several of which rank for law firm queries, direct attorneys to the wrong entity type.
Because a sole proprietor is personally liable for every contract the practice signs — office leases, equipment, vendor agreements. If the firm cannot pay, the claim is against your personal assets. A PLLC separates them. It does not, however, shield you from your own malpractice.
$385 annually for attorneys admitted before January 1, 2025, and nothing at all for those admitted since. The reduced $121 early-career fee was eliminated effective October 2024, so there is no longer any intermediate rate sitting between free and the full amount.
No. Illinois has no brick-and-mortar requirement, and ABA Formal Opinion 498 confirms a practice may be entirely virtual. The address you designate for ARDC registration appears on the public master roll, which is why most attorneys use something other than their home.
Client funds go into an interest-bearing account at an ARDC-eligible institution, with nominal or short-term funds pooled in an IOLTA account. Rules 1.15, 1.15A and 1.15B require monthly three-way reconciliation, a separate ledger for each client matter, and seven-year record retention.
No, Illinois does not require it. Rule 756(e) requires annual disclosure of whether you carry coverage, and private-practice attorneys reporting none must complete the ARDC’s four-hour PMBR self-assessment every two years. Most carry it anyway, since first-year premiums typically run under $1,000.
A five-digit number issued by the Clerk of the Circuit Court, separate from your ARDC number, required before you can e-file in Cook County. Attorneys leaving a firm must obtain their own rather than continuing to use their former firm’s.
The Odyssey eFileIL service itself charges no fee, though statutory court filing fees and payment processing charges still apply to each filing. E-filing has been mandatory in Illinois civil cases since January 2018, and paid filing service providers remain entirely optional.
vLex Fastcase legal research, which sells standalone at $695 a year, plus fifteen hours of on-demand CLE and daily Illinois case digests. Membership is free in your first year after admission, $75 for years two and three, rising to $455 at eleven years.
The filings can be done in an afternoon. What takes time is everything around them — deciding on space, setting up trust accounting properly, and telling people you have launched. That last item is the one most commonly delayed and the most expensive to delay.
The part that isn’t on any list
I’ve watched more than fifty attorneys launch practices through Chicago-Kent’s incubator programme, where we’ve provided space and services free since 2013, and a good many more besides.
Here’s what I’d tell you that doesn’t appear on any checklist.
The filings are the easy part. You can do all of them in an afternoon, and nobody fails because they filed the wrong form. The hard parts are the ones with no deadline attached — working out your runway honestly, telling people you’ve started before you feel ready, and deciding whether you’re going to do this alone.
The attorneys who struggle are almost never the ones who spent too much on an office. They’re the ones who ran out of money in month seven with work in the pipeline that hadn’t paid yet.
And the ones still practising in year five are, nearly without exception, the ones who built a referral network in year one.
Everything else on this page is mechanics. Those three things are the practice.
Ron Bockstahler is the founder and CEO of Amata Law Office Suites, a vendor member of the Chicago Bar Association, supporting Chicago-area law firms since 2002. He co-hosts The 1958 Lawyer podcast.
Amata Law Office Suites is not a law firm and does not provide legal services to the general public. This article is general information, not legal, tax, or financial advice. Fees, rules and requirements change — verify current figures with the ARDC, the Illinois Secretary of State, IDFPR, and the Illinois State Bar Association before relying on them.
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