An accessory dwelling may be subject to more than one limit at a time. A zoning rule can cap the number or configuration of units. A public grant, loan, tax benefit, or fee waiver can add occupancy, rent, or transfer conditions. A recorded covenant may continue to bind later owners. Private financing, association, or insurance terms can create separate obligations. Do not treat one of these layers as if it were the whole rule.
Confirm the unit-count rule
Check the current definition of the principal dwelling and each accessory unit, then confirm the maximum count for the parcel and the allowed configuration. Some authorities count attached and detached units together; others distinguish an internal suite, a junior unit, a garden suite, or a temporary structure. The answer may also depend on lot type, servicing, prior approvals, or the project’s construction date.
Local rules illustrate this variation. New York City’s ADU FAQ describes a one-ADU-per-home or tax-lot boundary in its stated framework. Fort Frances, Ontario, sets a different configuration in its 2025 Official Plan for qualifying municipally serviced lots, including conditions for combining an additional residential unit with a Garden Suite. See the Fort Frances configuration and Garden Suite guide for the Town’s stated conditions. Neither example determines what is allowed on another property, or even whether a given parcel meets the local conditions.
Maine’s statute gives a different unit-count example: municipalities must allow at least one ADU on a lot with a single-family dwelling in covered areas, and one ADU is excluded from density calculations. Implementation timing, water and wastewater rules, and a watershed exception still need checking; the Maine guide keeps those limits with the state rule. Milwaukee’s City summary, by contrast, says no more than one ADU is allowed on a property and places owner occupancy at the permit-submission stage. A stated maximum or density exemption does not replace the local eligibility test.
Read the complete program terms
If an owner received funding, a tax exemption, fee relief, or other assistance, obtain the signed agreement and current program rules. Record the benefit, administrator, eligibility test, trigger date, duration, required proof, and what happens after a sale or transfer. A program may require owner residence, impose affordable-rent or tenant conditions, limit short-term use, or require annual reporting. These terms are not automatically general zoning rules.
For example, New York City’s Plus One ADU financing materials describe an annual affidavit confirming that the property remains the recipient’s primary residence. San Diego’s separate-conveyance guidance identifies additional restrictions where housing-assistance or affordability covenants apply. Those examples show why an owner should review the actual award and recorded documents instead of assuming that a benefit ends when construction is complete.
D.C.’s affordable-ADU program provides another covenant-specific example. DHCD says an owner subject to a primary-residence covenant may not rent the ADU unless the recorded covenant allows a waiver and the agency approves one under exceptional circumstances. An approved conditional waiver requires annual certification, and it does not waive separate condominium, cooperative, or financing restrictions. The actual covenant and written decision control; this is not a general rule for all District ADUs.
For a separate-sale program, unincorporated San Diego County’s amendments effective September 18, 2026 add a right-of-first-refusal contract, a new-buyer primary-residence affidavit, and a public-listing disclosure. The County’s summary does not state the defined periods, so check the operative code and forms before relying on a duration. See the updated County separate-sale guide; these conditions do not apply to the City of San Diego.
England’s residential-annex CIL exemption is another use-linked condition: the main home must meet the principal-residence and material-interest tests, and the annex must meet the curtilage and single-dwelling criteria. Letting the annex or selling either property separately within the three-year clawback period can withdraw the exemption. See the England CIL annexe guide for the pre-commencement claim and notification steps. This is a charge exemption with a specific use condition, not a planning permission or a general rule for annexes elsewhere.
Check for recorded and private obligations
Search the current title for covenants and notices, and read any HOA, condominium, or lender documents that apply. Confirm whether the condition binds successors, how compliance is monitored, whether it can be amended or discharged, and which office can confirm its current status. A permit file may not contain every private agreement, and an agreement may outlast the program that first created it.
Before relying on a unit-count or affordability answer, verify the parcel, unit classification, effective date, permit and occupancy records, current program status, and recorded instruments. Ask the authority or program administrator to confirm the exact rule in writing. This article explains how to separate the layers; it does not establish a parcel-specific right or provide financing, tenancy, or legal advice.