To add a member to an LLC in Illinois, you need approval from your existing members under your operating agreement, a signed document admitting the new member on specific terms, and follow-through on the federal and state tax changes that come with having an additional owner. A filing with the Illinois Secretary of State is only required if the new member will serve as a manager.
Get Approval Under Your Operating Agreement
Start with your operating agreement. If it sets out a procedure for admitting new members, follow it exactly. Most agreements call for either a unanimous or majority vote of the existing members, written notice, and a defined waiting period. Those terms control.
If your LLC has no written operating agreement, the Illinois Limited Liability Company Act fills the gap. A person can become a member of an existing LLC only with the consent of every current member, unless the operating agreement says otherwise.1Illinois General Assembly. 805 ILCS 180 Limited Liability Company Act – Section 30-1
Illinois doesn’t require LLCs to have a written operating agreement, but adding a member without one is risky. The statutory defaults may not match what you and your co-members actually want on profit splits, voting, or management authority. If you don’t have a written agreement yet, draft one at the same time you admit the new member.
Put the Admission in Writing
Once the existing members approve, document the terms. You can either amend the current operating agreement or create a standalone admission agreement that the operating agreement incorporates by reference. Either way, the document needs to cover the terms that matter.
- What the new member is contributing — cash, property, or services — and the agreed value of any non-cash contribution.
- The new member’s ownership percentage and how existing members’ percentages adjust to make room.
- How profits and losses are allocated. This doesn’t have to track ownership percentages, but the allocation needs substantial economic effect under federal tax rules to hold up with the IRS.
- Voting rights: whether the new member votes on everything or only on certain decisions, and the weight of that vote.
- Management role. Under Illinois law, an LLC is member-managed unless the operating agreement expressly provides for manager management.2Illinois General Assembly. 805 ILCS 180/15-1
- Capital accounts for each member, tracking contributions, distributions, and allocated profits and losses over time.
- Buyout and exit terms. Skipping this provision is how LLC disputes become lawsuits.
Every member — existing and incoming — should sign. An unsigned understanding is worth nothing when a disagreement surfaces two years later.
When You Have to File With the Secretary of State
Illinois Articles of Organization don’t list every member. They list managers and any members who hold manager authority.3Illinois General Assembly. 805 ILCS 180 Limited Liability Company Act – Section 5-5 If the new member is joining as a passive owner without management authority, there’s nothing to amend in your state filings. The admission is handled entirely through your internal documents.
If the new member will serve as a manager or hold manager-level authority, file Articles of Amendment on Form LLC-5.25 with the Secretary of State. The form has a checkbox for “Admission of a new manager” and asks for the new manager’s name and address.4Illinois Secretary of State. LLC Articles of Amendment Form LLC-5.25 The filing fee is $50.5Illinois Secretary of State. Limited Liability Company Publications and Forms
Keep the rest of your state record current regardless. Changes to the registered agent, principal office, or overall management structure trigger their own filing obligations.
Federal Tax Consequences of Going From One Member to Two
If you’re going from one member to two, this is where the real work is. A single-member LLC is treated as a disregarded entity for federal income tax, with everything reported on the owner’s personal return. The moment a second member joins, the LLC automatically becomes a partnership for federal tax purposes.6Internal Revenue Service. LLC Filing as a Corporation or Partnership
The reclassification happens by default. You don’t file anything to make it happen, and you can only opt out by electing corporate tax treatment on Form 8832.6Internal Revenue Service. LLC Filing as a Corporation or Partnership Most small LLCs stay with partnership treatment.
You May Need a New EIN
If the single-member LLC used the owner’s Social Security Number as its tax ID, the shift to partnership status requires a new Employer Identification Number. The IRS treats this as a change in entity structure that calls for a fresh EIN.7Internal Revenue Service. When to Get a New EIN Apply online at irs.gov; the number is issued immediately. Then update your bank accounts, payroll systems, and vendor W-9s.
Partnership Return and Schedule K-1s
As a partnership, the LLC itself doesn’t pay federal income tax. It files Form 1065 each year reporting its total income, deductions, and credits, and issues each member a Schedule K-1 showing their share of those items for use on their personal return.8Internal Revenue Service. About Form 1065, U.S. Return of Partnership Income – Schedule K-1
Form 1065 is due by the 15th day of the third month after the tax year ends — March 15 for calendar-year LLCs.9Internal Revenue Service. Starting or Ending a Business That’s a month earlier than the personal return deadline. If the new member joins mid-year, you may need a short-year return for the pre-change period and a partnership return for the period after.
Self-Employment Tax
Members of a multi-member LLC taxed as a partnership are generally self-employed for federal tax purposes. If net self-employment earnings exceed $400, self-employment tax applies at a combined 15.3% rate, covering Social Security (12.4%) and Medicare (2.9%), on 92.35% of net earnings. An additional 0.9% Medicare tax applies to self-employment income above $250,000 for joint filers, $125,000 for married filing separately, and $200,000 for everyone else.10Internal Revenue Service. Topic No. 554, Self-Employment Tax
This catches new LLC members off guard. As an employee, half of the equivalent payroll taxes are invisible because the employer pays them. As an LLC member, you pay both halves. Budget for it.
Illinois Tax Filings That Kick In
Illinois adds its own obligations once the LLC is taxed as a partnership. The LLC must file Form IL-1065, the Partnership Replacement Tax Return. The replacement tax (formally the Personal Property Replacement Tax) applies to the LLC’s net income at 1.5%. Unlike Form 1065, this is an actual tax the LLC pays. Form IL-1065 is due by the 15th day of the fourth month after the tax year ends, so April 15 for calendar-year filers.11Illinois Department of Revenue. Partnerships Illinois grants an automatic six-month filing extension, but any tax owed is still due by the original deadline.
Illinois also offers an elective pass-through entity tax at 4.95% of the LLC’s net income. If the LLC makes the election, each member receives a credit against their own Illinois income tax for their share of the PTE tax paid.12Illinois Department of Revenue. Pub-129, Pass-Through Entity Information Whether the election saves money depends on each member’s situation.
If any member is a nonresident of Illinois, the LLC must either make pass-through withholding payments on that member’s behalf or collect a certificate of exemption from them. Partnerships that elect the PTE tax and expect combined replacement tax and PTE tax liability above $500 also owe quarterly estimated payments.12Illinois Department of Revenue. Pub-129, Pass-Through Entity Information
What You Owe the Incoming Member
LLC membership interests can qualify as securities under federal law, which means issuing one to a new member can technically be a securities offering. Most private LLCs rely on the Rule 506(b) exemption under Regulation D, which allows sales to an unlimited number of accredited investors and up to 35 non-accredited investors who are financially sophisticated, provided there is no general advertising.
For a two-person LLC adding a friend as a third member, formal securities compliance often feels excessive, but the exposure is real. If the new member later claims they were misled about the LLC’s finances or prospects, securities fraud is a far more dangerous allegation than breach of contract. At a minimum, give the incoming member the LLC’s financial statements, tax returns, and any material information about debts or pending litigation before they sign. For larger LLCs or significant capital contributions, consult a securities attorney and consider filing a Form D with the SEC.
Beneficial Ownership Reporting Status
The Corporate Transparency Act originally would have required most LLCs to report beneficial ownership information to FinCEN, including updates within 30 days of adding a member who owns 25% or more. As of March 2025, FinCEN published an interim final rule exempting all U.S.-formed entities from BOI reporting, and FinCEN has stated it will not enforce penalties against U.S. citizens or domestic reporting companies under the current or revised rules.13Financial Crimes Enforcement Network. Beneficial Ownership Information Reporting That exemption may change if new rulemaking occurs, so check FinCEN’s website before you assume the obligation doesn’t apply.