Chicago, IL Accessory Structures: ADU Impact Fees (2026)
Key Facts
- Registration fee
- $500 per Affordable ADU
- Trigger
- 2+ ADUs added after May 1, 2021
- Affordability share
- 50% of new ADUs
- Affordability term
- 30 years from recorded notice
- Violation fine
- $500 per day
Summary
Chicago charges a $500 Affordable ADU Initial Registration Fee for each coach house or conversion unit an owner must keep affordable when a building adds two or more ADUs.
two or more ADUs are added, either separately or in any combination, at any time after May 1, 2021, to a residential building other than to a residential building owned, operated or maintained by the Chicago Housing Authority, the owner of such building shall maintain 50% of those newly added ADUs as affordable housing units for the duration of the affordability requirement as set forth in subsection (i) of this section; provided, however, that if this 50% calculation results in a fractional number, any such fractional result shall be rounded down to the nearest integer. This subsection
(d) shall run with the land and be enforceable against any subsequent owner.
(e) Registration. Prior to the application by a building owner for a building permit with the Department of Buildings for an ADU, the Department of Housing will advise the owner whether any of the proposed ADUs are required to be maintained as affordable housing units. If the owner is required under this section to maintain any of the proposed ADUs as affordable housing units, the owner shall register those designated Affordable ADUs with the Department of Housing in accordance with rules duly promulgated by the Commissioner. Such registration shall be accompanied by the Affordable ADU Initial Registration Fee for each Affordable ADU, as set forth in Section 2-44-065, to defray the costs of administering this section.
(f) Recorded notice – Required. For each Affordable ADU, the Department of
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-74: Current through Council Journal of June 17, 2026).
Full Breakdown
Under the Additional Dwelling Unit Ordinance, once a residential building adds two or more coach houses or conversion units (together, ADUs) after May 1, 2021, the owner must keep 50% of the newly added units affordable to households at or below 60% of area median income for 30 years. Before the Department of Buildings can issue a permit, the owner registers each Affordable ADU with the Department of Housing and pays the $500 Affordable ADU Initial Registration Fee per unit, set in the citywide fee schedule, to cover the cost of administering the program. Buildings owned by the Chicago Housing Authority are exempt, and single-ADU additions don't trigger the requirement.
Violations & Fines
Owners of an Affordable ADU who violate the section face a $500 fine per offense, with each day a violation continues counted as a separate offense; tenants can also sue for injunctive relief, treble damages, and attorney fees.
Frequently Asked Questions
Does every new ADU in Chicago owe this fee?
Can a permit be issued before the fee is paid?
Sources & Official References
Other rules in Chicago
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