San Mateo County is offering an amnesty program for existing accessory dwelling units (aka granny units, in-law units) constructed without some or all necessary permits and approvals.

This program will run for a limited term, and offers owners of unpermitted units the opportunity to bring their unit into compliance with basic health and life safety standards without the risk of code enforcement action, and with significant fee reductions and assistance in determining necessary improvements.

The amnesty program is in an initial pilot phase, and is not yet open to the general public. To inquire about the availability of the program, please contact:

William Gibson, Planner III

    Accessory Dwelling Units

    Accessory dwelling units, also known as in-law units or granny units, are dwelling units built within, attached to, or detached from an existing primary residence. They may be built within a converted garage or accessory structure, as a newly built structure, or as a conversion of part of a main house. Typically, accessory dwelling units are much smaller than the main house, and can offer convenient and affordable for adult children or extended family, and/or a source of income for homeowners.

    Unpermitted Accessory Dwelling Units

    While most accessory dwelling units in the County are built with all required permits and approvals, some units have been constructed without following the required procedures. Some of these units may be safe and fully habitable and simply did not receive proper permits. In other cases, the construction standards may not meet code requirements and may present health and safety issues to residents and adjacent properties. The Accessory Dwelling Unit Amnesty program is intended to provide a low-cost, penalty-free pathway to improve all unpermitted accessory dwelling units to a safe and habitable condition without requiring the removal of the units or displacement of any residents.

    Benefits of the Program
    • Low-cost initial inspection of the unpermitted unit
    • Detailed guidance on required improvements
    • Waiver of all fees and penalties for unpermitted construction
    • Significant reduction or waiver of planning, building, and other permit fees
    • Alternative, more easily achievable compliance standards
    • Assurance that the accessory dwelling unit is habitable and does not present risks to inhabitants
    • Suspension of code enforcement action for any issues identified and improvements made through the amnesty program
    • The opportunity to explore the program, prior to formal application, without risk of any penalty or enforcement
    • A certification record, which will be supplied to the applicant and kept on file at the County, memorializing the improvements and assuring that there will be no subsequent code enforcement related to those improvements
    Learn More Eligibility The Process Fees

    Accessory Dwelling Unit Amnesty Program Brochure

    Limited Window of Opportunity

    The amnesty program will only run for a limited time, between one and three years, beginning in October/November 2018. To take advantage of this opportunity, applicants must apply within that period, although after application, completion of improvements to the unit may extend beyond the formal amnesty period.


    To schedule a consultation with County staff, and begin the process of exploring the amnesty program, with no risk of any code enforcement action, contact:

    William Gibson
    (628) 222-3082

    Rehabilitation Loan Program

    For some eligible applicants, there may be rehabilitation loans available through the County’s Housing Department. Not every applicant will qualify for these loans, but for eligible applicants, they can help support the cost of unit repairs and improvements. For more information see the County's Accessory Dwelling Unit Amnesty Loan Program.

    For more information, see the Accessory Dwelling Unit Amnesty and Loan Program FAQ

    Other Accessory Dwelling Unit Amnesty Materials
    Other Accessory Dwelling Unit Materials
    Accessory Dwelling Unit Calculator

    While the County cannot provide detailed guidance on the potential costs of work and materials, there is a Accessory Dwelling Unit Calculator that provides general information on the cost of constructing a new unit in San Mateo County, which may help you form rough estimates of the possible range of costs before approaching a contractor.