Senate File 592 - Enrolled Senate File 592 AN ACT RELATING TO COUNTY AND CITY REGULATION OF ACCESSORY DWELLING UNITS. BE IT ENACTED BY THE GENERAL ASSEMBLY OF THE STATE OF IOWA: Section 1. Section 331.301, Code 2025, is amended by adding the following new subsection: NEW SUBSECTION . 27. a. A county shall allow a minimum of one accessory dwelling unit on the same lot as a single family residence in accordance with the following conditions: (1) An accessory dwelling unit shall comply with all applicable building regulations as defined in chapter 103A. (2) An accessory dwelling unit shall not exceed one thousand square feet or fifty percent of the size of the single family residence, whichever is larger. (3) An accessory dwelling unit shall be prohibited or limited only to the extent that a state historic building code restriction, as adopted by a county in accordance with section 103A.43, subsection 3, a deed restriction, or a rule of a common interest community, as defined in section 499C.1, limits or prohibits the construction or use of an accessory dwelling unit. The imposition of an ordinance, motion, resolution, or amendment regulating accessory dwelling units that is more restrictive when applied to a common interest community than when applied to a single family residence is prohibited. (4) If a manufactured home as defined in section 435.1, subsection 3, or a mobile home as defined in section 435.1,

Senate File 592, p. 2 subsection 5, is used as an accessory dwelling unit, the manufactured home or mobile home shall be converted to real property by being placed on a permanent foundation and assessed for real estate taxes pursuant to section 435.26. b. Except as otherwise provided in paragraph “a” or by state law, a county shall not impose any of the following limitations or restrictions: (1) Requirements related to the placement or appearance of an accessory dwelling unit that are more restrictive than those imposed on a single family residence including but not limited to the following: maximum building heights; minimum setback requirements; minimum lot sizes; minimum building frontages; maximum lot coverages; density requirements; and aesthetic or architectural standards or requirements. Additionally, a county shall not require an accessory dwelling unit to match the exterior design, roof pitch, or finishing materials of the single family residence. (2) Regulations on the use of an accessory dwelling unit as a rental property that are more restrictive than those provided for in subsection 18 of this section and chapter 562A. (3) A requirement that the lot containing a single family residence and an accessory dwelling unit have additional parking beyond that required for a single family residence or payment of a fee in lieu of providing additional parking. (4) Restrictions on the occupancy of either the single family residence or the accessory dwelling unit by any of the following manners: requiring the property owner to be a resident; requiring a familial, marital, or employment relationship to exist between the occupants of the single family residence and the occupants of the accessory dwelling unit; or restricting the occupancy of an accessory dwelling unit based on income or age. (5) The requirement of new or separate utility lines between the accessory dwelling unit and public utility service connections. However, if full utility access that includes a separate metering system for billing purposes cannot be provided to the accessory dwelling unit, then the county can require new or separate utility lines. (6) Imposition of a different county impact fee structure or

Senate File 592, p. 3 development standard for an accessory dwelling unit than those used for the single family residence on the same lot. (7) The requirement of improvements or repairs to public streets or sidewalks beyond those imposed on the single family residence on the same lot. c. A county shall approve an accessory dwelling unit permit application that meets the requirements set forth in paragraph “a” and by state law without discretionary review or hearing and consistent with the time frame assigned to the approval of a single family residence. An accessory dwelling unit permit application shall not have a review timeline or schedule in excess of a county’s normal review schedule for a single family residence. If the county denies an accessory dwelling unit permit, the reason for denial shall be provided in writing to the applicant and include any remedy necessary to secure approval. d. A county ordinance, motion, resolution, or amendment regulating accessory dwelling units in a manner that conflicts with this subsection is void. Nothing in this subsection prohibits a county from adopting an ordinance, motion, resolution, or amendment that is more permissive than the requirements provided in this subsection. e. For the purposes of this subsection: (1) “Accessory dwelling unit” means an additional residential dwelling unit located on the same lot as a single family residence that is either attached to or detached from the single family residence. (2) “Detached” includes being part of any accessory structure such as a detached garage. (3) “Dwelling unit” means the same as defined in section 562A.6, subsection 3. (4) “Single family residence” means the same as defined in section 562A.6, subsection 15, except to the extent that a single family residence may share utility lines with the accessory dwelling unit if full utility access that includes a separate metering system for billing purposes can be provided to the accessory dwelling unit. Sec. 2. Section 364.3, Code 2025, is amended by adding the following new subsection:

Senate File 592, p. 4 NEW SUBSECTION . 20. a. A city shall allow a minimum of one accessory dwelling unit on the same lot as a single family residence in accordance with the following conditions: (1) An accessory dwelling unit shall comply with all applicable building regulations as defined in chapter 103A. (2) An accessory dwelling unit shall not exceed one thousand square feet or fifty percent of the size of the single family residence, whichever is larger. (3) An accessory dwelling unit shall be prohibited or limited only to the extent that a state historic building code restriction, as adopted by a city in accordance with section 103A.43, subsection 3, a deed restriction, or a rule of a common interest community, as defined in section 499C.1, limits or prohibits the construction or use of an accessory dwelling unit. The imposition of an ordinance, motion, resolution, or amendment regulating accessory dwelling units that is more restrictive when applied to a common interest community than when applied to a single family residence is prohibited. (4) If a manufactured home as defined in section 435.1, subsection 3, or a mobile home as defined in section 435.1, subsection 5, is used as an accessory dwelling unit, the manufactured home or mobile home shall be converted to real property by being placed on a permanent foundation and assessed for real estate taxes pursuant to section 435.26. b. Except as otherwise provided in paragraph “a” or by state law, a city shall not impose any of the following limitations or restrictions: (1) Requirements related to the placement or appearance of an accessory dwelling unit that are more restrictive than those imposed on a single family residence including but not limited to the following: maximum building heights; minimum setback requirements; minimum lot sizes; minimum building frontages; maximum lot coverages; density requirements; and aesthetic or architectural standards or requirements. Additionally, a city shall not require an accessory dwelling unit to match the exterior design, roof pitch, or finishing materials of the single family residence. (2) Regulations on the use of an accessory dwelling unit as a rental property that are more restrictive than those provided

Senate File 592, p. 5 for in subsections 9 and 16 of this section, section 414.1, subsection 1, paragraph “e” , and chapter 562A. (3) A requirement that the lot containing a single family residence and an accessory dwelling unit have additional parking beyond that required for a single-family residence or payment of a fee in lieu of providing additional parking. (4) Restrictions on the occupancy of either the single family residence or the accessory dwelling unit by any of the following manners: requiring the property owner to be a resident; requiring a familial, marital, or employment relationship to exist between the occupants of the single family residence and the occupants of the accessory dwelling unit; or restricting the occupancy of an accessory dwelling unit based on income or age. (5) A requirement of new or separate utility lines between the accessory dwelling unit and public utility service connections. However, if full utility access that includes a separate metering system for billing purposes cannot be provided to the accessory dwelling unit, then the city can require new or separate utility lines. (6) Imposition of a different city impact fee structure or development standard for an accessory dwelling unit than those used for the single family residence on the same lot. (7) The requirement of improvements or repairs to public streets or sidewalks beyond those imposed on the single family residence on the same lot. c. A city shall approve an accessory dwelling unit permit application that meets the requirements set forth in paragraph “a” and by state law without discretionary review or hearing and consistent with the time frame assigned to the approval of a single family residence. An accessory dwelling unit permit application shall not have a review timeline or schedule in excess of a city’s normal review schedule for a single family residence. If the city denies an accessory dwelling unit permit, the reason for denial shall be provided in writing to the applicant and include any remedy necessary to secure approval. d. A city ordinance, motion, resolution, or amendment regulating accessory dwelling units in a manner that conflicts

Senate File 592, p. 6 with this subsection is void. Nothing in this subsection prohibits a city from adopting an ordinance, motion, resolution, or amendment that is more permissive than the requirements provided in this subsection. e. For the purposes of this subsection: (1) “Accessory dwelling unit” means an additional residential dwelling unit located on the same lot as a single family residence that is either attached to or detached from the single family residence. (2) “Detached” includes being part of an accessory structure such as a detached garage. (3) “Dwelling unit” means the same as defined in section 562A.6, subsection 3. (4) “Single family residence” means the same as defined in section 562A.6, subsection 15, except to the extent that a single family residence may share utility lines with the accessory dwelling unit if full utility access that includes a separate metering system for billing purposes can be provided to the accessory dwelling unit. ______________________________ AMY SINCLAIR President of the Senate ______________________________ PAT GRASSLEY Speaker of the House I hereby certify that this bill originated in the Senate and is known as Senate File 592, Ninety-first General Assembly. ______________________________ W. CHARLES SMITHSON Secretary of the Senate Approved _______________, 2025 ______________________________ KIM REYNOLDS Governor