Most buyers who see "Williamson Act" or "agricultural preserve" in a San Martin disclosure package read it the same way: a permanent discount, tied to the dirt, that transfers to whoever owns the land next. The county assesses the parcel on what it earns as farmland instead of what it would sell for, the tax bill stays low, and that's that.
For two specific San Martin subdivisions, that's not what's happening. Santa Clara County has already started the clock on ending the discount, parcel by parcel, and the ending was set in motion years before any current owner listed their property.
The subdivisions the county named by contract number
Santa Clara County's Department of Planning and Development runs a public page tracking its Williamson Act program, and it lists something most listing agents never mention: a completed Phase I round of county-initiated non-renewal actions, targeted at parcels under 5 acres and at two named subdivisions specifically. The county's own language calls out Golden Heights Estates (Contract 68.084) and San Martin Estates (Contract 75.004) by name.
That second one is worth sitting with if you're shopping acreage in San Martin, because "San Martin Estates" isn't a marketing label. It's a real subdivision with real history. The Morgan Hill Times traced it back to the old Hayes Valley Ranch, where a 1975 Williamson Act contract covered roughly 870 acres of grazing land. By the early 1980s, a group of developers had split that land into more than 40 parcels of about 20 acres each, sold as country home sites. Those parcels have changed hands more than 120 times since. Cattle mostly stopped grazing there decades ago. The land became, in the paper's description, "natural habitat for country homes and retirement estates," including at least one property with a castle under construction.
The contract followed the land through every one of those sales anyway, because that's how the Williamson Act works. It runs with the parcel, not the owner. Whoever buys next inherits whatever stage the contract is in.
What the contract actually promises, and what it doesn't
A Williamson Act contract is a deal between a landowner and the county. The owner agrees to keep the land in agricultural or open-space use. In exchange, the county assessor values the parcel based on what it earns as farmland, not what it would sell for on the open market. Santa Clara County estimates that gap can save an enrolled landowner meaningfully.
The standard term is 10 years, and it renews automatically every January 1 unless someone files paperwork to stop that. That's the part buyers usually understand. What's less obvious is what happens once someone does file.
A landowner who wants out has to submit a notice of non-renewal to the Clerk of the Board by October 1. Once that's filed, the contract stops adding years and starts counting down, nine years remaining as of the following January 1. During those nine years, every restriction in the contract still applies. Only the tax benefit changes, stepping back toward full market value as the clock runs out. The other exit, cancellation, is faster but expensive: the county can approve it only under specific findings, and the landowner has to pay a fee equal to 12.5 percent of the property's unrestricted fair market value. State guidance treats cancellation as the disfavored option precisely because it's meant to be hard.
Here's the part that changes the math for a San Martin buyer: the county doesn't need the landowner to file anything. It can non-renew a contract on its own, and it already did, specifically naming the San Martin Estates and Golden Heights Estates subdivisions in its Phase I action. If you're looking at a parcel inside either of those tracts, the nine-year countdown may already be running, started by the county rather than by whoever currently holds title.
Why the same discount can be nearly free on one parcel and expensive on the next
Santa Clara County's general plan now requires 20-acre minimum lots for hillside development. That single rule quietly changes what a Williamson Act contract actually costs a hillside owner. If your parcel already can't be subdivided or built out further under county zoning, the contract's use restriction isn't taking anything away from you. You get the tax discount for agreeing not to do something you couldn't have done anyway.
That's the mechanism that makes San Martin acreage listings hard to compare on price alone. Two 20-acre parcels in the same subdivision, similar homes, similar creek frontage, can carry very different real costs depending on where each one sits in its contract's life. A parcel with a fresh 10-year rolling term and no compliance issues is close to a no-cost discount for an owner who has no plans to farm or subdivide. A parcel the county already flagged for non-renewal, like ones inside San Martin Estates, is instead sitting on a fixed nine-year runway toward a higher assessed value, and that runway doesn't reset just because the property changes hands.
Neither situation shows up in a listing photo. Both show up in the contract file at the Clerk of the Board.
What to check before you remove contingencies
If you're under contract on San Martin acreage, or advising a seller on how to price it, a few specific questions settle this before it becomes a surprise at year eight of ownership:
- Ask for the parcel's Assessor's Parcel Number and pull the actual contract, not just a disclosure checkbox. The Clerk of the Board's Williamson Act program maintains the file and can confirm which contract number, if any, applies to that specific APN.
- Ask directly whether a notice of non-renewal has already been filed or county-initiated, and if so, what year the nine-year clock started. For anything inside San Martin Estates or Golden Heights Estates, assume it's worth confirming even if the seller says they haven't touched the contract themselves.
- Check the parcel's history with the annual Agricultural Preserve Questionnaire, due to the Assessor's Office every April 10. Santa Clara County can open a non-renewal on its own if that questionnaire goes unreturned, so a pattern of late or missing filings is itself a signal.
- Confirm the seller has provided the disclosure required under County Ordinance Code Section C13-25, which requires the transferor to disclose the contract and the buyer to sign off before the sale completes. This is a closing document, not an optional courtesy.
- If you intend to actually farm the land, ask whether the parcel has a documented history of commercial agricultural use. The county's compliance reviews look at exactly that, and a parcel with no working agriculture is a more likely candidate for future non-renewal even outside the named subdivisions.
None of this changes what the land is worth to you as a place to live. It changes what your property tax bill looks like in year five versus year nine, and whether that trajectory is already locked in before you sign anything.
Frequently asked questions
If I buy a parcel where non-renewal already started, can I stop it? Generally no. Once a contract enters its non-renewal period, the restrictions and the phase-out both continue on schedule regardless of who owns the land. A new owner can apply for cancellation instead, but that requires county findings and the 12.5 percent fee, and state guidance treats cancellation as the exception, not the routine path.
Does a Williamson Act contract ever convert to something else, like solar? There's a narrow path for that. State law allows a contract to be rescinded into a solar-use easement instead of cancelled outright, but that authorization lapsed in 2020 and was reinstated in January 2023, and take-up has been limited statewide. It's not a common outcome for a residential acreage buyer to plan around.
If I'm not farming and don't care about the tax savings, does any of this matter? It matters at resale even if it doesn't matter to you day to day. A future buyer will ask the same questions you should be asking now, and a contract in an active non-renewal period is a fact about the parcel that shows up in title work whether or not either owner farms.
If you're weighing a specific San Martin parcel and want a straight read on where its Williamson Act contract actually stands, that's the kind of question worth running down before you write an offer, not after. Sold By Team Robinson can help you pull the right file and ask the county the right questions. Get a Free Home Valuation and let's talk through what your parcel's contract history means for your numbers.
