If an older Marin County permit or tax record carries an APN that no longer works, preserve that number before searching under the current parcel. Ask the County Assessor whether its Dead Parcel History Report connects the retired APN to one or more successor APNs, then search County building and planning records under each documented identifier and the property address. The report is an assessment-record bridge; it does not establish title, legal boundaries, permit approval or completed work.
Build the parcel identity trail first
Marin County’s Assessor Mapping Division says an APN can change for administrative mapping reasons, land divisions, lot-line adjustments, mergers, parcel combinations or tax-rate-area changes. A recorded map or deed processed during one calendar year may take effect for the following property-tax roll year. That timing can leave an older permit and a current assessment record under different numbers.
Keep these items as separate entries rather than replacing the old APN in your notes:
- Retired APN: Copy it exactly from the older permit, tax notice, map or correspondence, including hyphens.
- Current candidate APN: Record where you found it and the roll or document date. Do not label it the successor until the County source connects the two.
- Change evidence: Save the approximate change year and any recorded-map, deed, project-file or map-page reference already available.
- Addresses: Keep the earlier address from the old record and the current address. An address match alone does not establish parcel lineage.
The County’s guide to reading an Assessor Parcel Map describes a map Change Box that can include the revision date, tax year, old and new APNs, block number and project file number. If you know the current APN or mapbook page, that box can supply another dated lead. The County cautions that Assessor maps are for assessment use and may not reflect subdivision or building rules, so treat the map as an identifier source rather than a boundary or development determination.
Request the Dead Parcel History connection
The County’s 2024–25 parcel-tax annual letter explains the report’s purpose: when a prior-year parcel was merged or segregated, the Dead Parcel History can identify the new APN or APNs to which a district may need to assign a charge. A later County user-fee study still lists the annual report as an Assessor service supplied per request. Neither document presents a public, self-service lookup for one property.
Use the current Assessor contact on the Mapping Division page to ask whether the report is available for the retired APN and relevant roll year, how it is supplied, and whether a current charge applies. Include the old APN, any candidate new APN, the approximate change year and the map or recorded-document reference you have. Ask for the predecessor-to-successor relationship and its effective roll year, rather than asking the Assessor to find a building permit.
For a fictional example, suppose an old permit lists APN 123-456-70, while a current notice lists 123-456-71 and 123-456-72 after a segregation. Do not combine the three numbers into one search string. First obtain County evidence showing which number is the predecessor and which are successors. Then keep the lineage as three dated entries and use each APN separately when searching for permits. These numbers are illustrative and were not queried.
Carry every documented APN into the permit search
Marin County’s Community Development Agency records search separates Building and Safety records from Planning records. Its instructions recommend an APN or address for permit and license searches. Use the branch that matches the document you need, then repeat a narrow search for the retired APN, each successor APN and the relevant address variation.
- Building record: Look for the permit number, record type, issue or application date, status, address and any documents associated with the same work.
- Planning record: Look for the planning case number, final decision, exhibits and technical reports tied to the property or proposal.
- Identity note: Record which APN and address produced each result. Do not silently move a permit found under the retired parcel onto every successor parcel.
This is where the Marin guide differs from a general permit lookup by address: the first task is documenting the parcel-number change, not trying more address spellings. An old permit can remain valid evidence of its own issue and scope while its APN has been retired. It does not, by itself, show how later parcel lines were allocated or whether work passed final inspection.
Send a named-record request when the online trail stops
If the CDA search does not expose the needed document, use Marin County’s public-record request page for a specifically described existing record. Name the responsible department, the retired and successor APNs, both address versions, the approximate permit or planning year, any case or permit number, and the exact item you want—for example, a permit card, final planning decision, inspection history or approved plan.
Keep custodian roles separate. The Assessor can document assessment identifiers; CDA holds County building and planning records; the Recorder maintains recorded maps and official real-property documents but states that it does not maintain building plans or blueprints. If the property’s permitting authority is a city or town rather than unincorporated Marin County, use that jurisdiction’s building or planning office. The Mapping Division explains that a postal city name does not determine the jurisdiction and points to the parcel’s Tax Rate Area as the County’s location check.
An empty current-APN search leaves the historical permit and planning file unresolved. It may mean the record remains under the retired APN, a former address, a separate record class or an offline County file. Preserve the identity chain and ask for the named record. The older building-permit lookup guide gives additional ways to narrow an archive request without treating a database miss as a legal conclusion.
Last checked October 5, 2026 (2026-10-05 UTC). Public guidance pages and two County source PDFs were reviewed. No individual property record, permit, planning case or map page was queried or retrieved, and no report or records request was submitted. Current report delivery or price was not independently tested.