Updated September 4, 2026. Quick answer: Illinois lets the board adopt a special assessment alone unless it pushes yearly assessments above 115 percent of last year’s total, letting owners holding 20 percent of the vote petition to reject it.
Key statute: 765 ILCS 605/18(a)(8) (Contents of bylaws, board/owner assessment procedure) together with 765 ILCS 605/9(c) (Budget and reserves) and 765 ILCS 605/9(g)-(h) (Lien), Illinois Condominium Property Act
How Illinois lets an association approve it
Illinois uses an owner-petition-triggered vote tied to a numeric budget-growth threshold. Under 765 ILCS 605/18(a)(8)(ii), if a special assessment would push “the sum of all regular and separate assessments payable in the current fiscal year exceeding 115% of the sum of all regular and separate assessments payable during the preceding fiscal year,” owners holding 20 percent of the votes can deliver a written petition within 14 days, which forces the board to “call a meeting of the unit owners within 30 days of the date of delivery of the petition to consider the budget or separate assessment”; the assessment is ratified “unless a majority of the total votes of the unit owners are cast at the meeting to reject the budget or separate assessment.” Below that 115% growth threshold, the board can adopt a special assessment without triggering this petition process. Assessments tied to emergencies or legal mandates skip the process entirely: “separate assessments for expenditures relating to emergencies or mandated by law may be adopted by the board of managers without being subject to unit owner approval,” with “emergency” defined as “an immediate danger to the structural integrity of the common elements or to the life, health, safety or property of the unit owners.” Capital additions face a higher bar instead: assessments for “additions and alterations to the common elements or to association-owned property not included in the adopted annual budget, shall be separately assessed and are subject to approval of two-thirds of the total votes of all unit owners.”
The notice you’re owed
Illinois ties special-assessment notice to its general membership-meeting rule. Under 765 ILCS 605/18(a)(8)(i), unit owners must receive “notice, in the same manner as is provided in this Act for membership meetings” of any board meeting to adopt the annual budget or a separate special assessment. That membership-meeting rule, at 765 ILCS 605/18(b)(6), requires that “written notice of any membership meeting shall be mailed or delivered giving members no less than 10 and no more than 30 days notice of the time, place and purpose of such meeting.”
Paying it: plan, interest, and late fees
Illinois doesn’t give owners a statutory right to demand a payment plan for a special assessment; 765 ILCS 605/9(f) leaves timing to the board: “Payment of any assessment shall be in amounts and at times determined by the board of managers.” The board itself does have the power to spread a special assessment out: 765 ILCS 605/18(a)(8)(vi) lets “the board of managers… adopt separate assessments payable over more than one fiscal year.” As for interest and late fees, the statute doesn’t fix a numeric rate or cap; 765 ILCS 605/9(g)(1) simply authorizes the lien to include “any interest, late charges, reasonable attorney fees incurred enforcing the covenants of the condominium instruments, rules and regulations of the board of managers, or any applicable statute or ordinance, and costs of collections,” leaving the actual rate and fee amount to the declaration, bylaws, or board.
Unpaid common expenses in Illinois, along with interest, late charges, attorney fees, and collection costs, “shall constitute a lien on the interest of the unit owner in the property prior to all other liens and encumbrances” under 765 ILCS 605/9(g)(1), and that lien can be foreclosed “in the same manner as a mortgage of real property” under 605/9(h).
Does Illinois require a reserve study?
No, not a mandatory one. Illinois requires reasonable reserve funding and disclosure, but commissioning a professional reserve study itself is optional, not required. 765 ILCS 605/9(c)(2) states that “all budgets adopted by a board of managers on or after July 1, 1990 shall provide for reasonable reserves for capital expenditures and deferred maintenance for repair or replacement of the common elements,” and lists factors the board must weigh in setting that amount, including “any independent professional reserve study which the association may obtain,” language that makes a study something the board may get, not something it must get. Associations can even vote to waive the reserve requirement altogether: 765 ILCS 605/9(c)(3) allows “an association without a reserve requirement in its condominium instruments” to “elect to waive in whole or in part the reserve requirements of this Section by a vote of 2/3 of the total votes of the association,” subject to a separate disclosure obligation if they do.
Honest gaps
The Illinois statute text on this page comes from a codified-text mirror of the Illinois Compiled Statutes rather than the state legislature’s own site, which could not be reached this session. The section numbers and figures were checked for internal consistency but were not cross-verified against a second Illinois-specific source.
Source note. Read from https://law.onecle.com/illinois/765ilcs605/18.html ; https://law.onecle.com/illinois/765ilcs605/9.html on September 4, 2026.
Related: HOA rules in a 55+ community · how a special-assessment foreclosure actually works · lump sum vs. a payment plan.
General information drawn from each state’s own statutes as read at its official legislature or code-publisher site (or a verbatim codified mirror where noted), not legal advice. Special-assessment law is state law, and every association’s own declaration and bylaws add rules on top of the statutory floor described here. We are not a law firm and this is not legal advice.