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STATE OF IOWA
KIM REYNOLDS
GOVERNOR
May 1,2025
The Honorable Paul Pate
Secretary of State of Iowa
State Capitol
Des Moines, Iowa 50319
Dear Mr. Secretary,
I hereby transmit:
Senate File 592, an Act relating to county and city regulation of accessory dwelling units.
The above Senate File is hereby approved on this date.
Sincarely
Kim Reynoh
Governor of Iowa
cc: Secretary of the Senate
Clerk of the House
STATR CAPITOL DES MOINES, IOWA 50319 515.281.5211 FAX 515.725.3527 WWW.GOVERNOR.IOWA.GOV
RIGHT
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Senate Pile 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 4990.1, 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 Pile 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 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
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 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 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
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 SINCmiR PAT GRASa2.EY
President of the Senate 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
Approved I V 1^ , 2025
^ary ra the Senate
KIMXREYNOLDS
Governor