Mariposa County sells its tax-defaulted property in a room, not on a website. The auction is at 10:00 a.m. on Thursday, August 6, 2026, in the Board of Supervisors’ Room at 5100 Bullion Street, and the way you get in is to show up at 9:00 a.m. with a $5,000 cashier’s check. There is no online platform, no pre-registration, and no deposit deadline weeks in advance.
That last part is worth sitting with, because it inverts the usual problem. Most California tax sales are decided before they open: Butte’s August auction took its final deposit on August 3, four days before bidding started, so anyone who found the list on August 4 was already out. Mariposa’s door is open until the morning of. The constraint here is not access. It is that you have three days to do the work.
So here is our read, published while the parcels are still live. This is a free pre-sale desk analysis: county records checked against county records. We did not inspect anything, pull title, walk a boundary, or call county planning. It is not advice and not a recommendation to bid on or avoid any parcel. The full sortable table is here, with a CSV.
What is actually in the sale
The county noticed 24 items. By the version of the notice we read, ten have been redeemed and one was removed, which leaves 13 still on the block. Redemption runs to the close of business on Wednesday, August 5, so that number can fall again before the gavel — a parcel you research tonight may not exist as a lot on Thursday.
The 13 break down as nine LAND ONLY and four LAND/IMPROVEMENTS, using the county’s own labels from the notice. They range from a 0.09-acre sliver to a 40-acre block, with minimum bids from $1,800.36 to $45,785.07 (median $8,409.61). Put end to end, the whole sale opens at about $175,000 against roughly $1.08 million of county assessed value.
We matched every one of the 13 to Mariposa County’s own assessor parcel layer — 13 of 13, no misses — to pull land value, structure value and acreage. That join is the entire reason this post has anything to say. Without it you have a list of prices with nothing to compare them to.
The thing that stands out
All 13 parcels open below their assessed value, between 0.11× and 0.58×, median 0.18×.
That sounds unremarkable until you set it beside the last sale we read this way. In San Bernardino’s July auction, roughly 72% of priced parcels opened at or above the county’s entire assessed value. That read was mostly an exercise in throwing things out — 858 of 1,250 parcels failed on price alone before anyone looked at what they were. Here, nothing fails that test. The whole list clears the bar, and the work changes from discarding to discriminating.
Why the difference is not mysterious. We wrote in what the opening bid measures that a California opening bid is mostly a fixed cost stack — the county’s cost of taking a parcel through a tax sale, which barely varies with what the parcel is worth. When that fixed floor lands on desert dirt assessed at $1,300, the bid towers over the value. When it lands on Sierra foothill land assessed in the tens or hundreds of thousands, it disappears into it.
Mariposa’s 13 lean toward the second case, and the pattern shows up inside the list too. The five parcels assessed under $25,000 carry a median ratio of 0.24×; the eight assessed above it come in at 0.14×. The cheapest parcel in the sale, item 5 at $1,800.36, is assessed at $3,587 — so its bid is half the value, the second-worst deal on the table despite being the lowest number on it. Cheap and cheap-relative-to-worth are not the same thing, and on a small list you can watch them come apart.
Treat the strength of that as directional, not settled. Thirteen parcels is a small sample, and one of them argues with the trend.
The one that does not fit
Item 9 is the worst ratio in the sale at 0.58× — a $15,722.77 opening bid on a 0.30-acre parcel assessed at $27,224. It is not one of the cheap outliers the fixed-cost story explains; it sits mid-table on assessed value and still prices badly. On a per-acre basis the county is asking about $52,000 an acre, far above anything else here.
We cannot tell you why from the notice. A minimum bid is built from what is owed, and an unusually large one usually means an unusually long or unusually expensive default — but the notice does not itemise, so that is a reading, not a fact. It is the parcel we would want explained before bidding, and the county is the only place to get that explanation.
The cost that is not in any of these numbers
Every one of the 13 is marked SPECIAL ASSESSMENTS in the notice, and the notice states directly that these are a lien on the property. Not one parcel escapes it.
This is the same mechanism the opening-bid post described, except Mariposa says it out loud rather than leaving you to infer it. A special assessment is a charge levied for a specific benefit or service — road districts, fire, water, sewer — and it rides with the parcel to the new owner. Whatever the ratio in our table says, it is computed against a bid that does not include this.
We have not priced them, because the notice does not carry the amounts and we will not estimate a number we cannot source. The county’s information packet and the Tax Collector’s office at (209) 966-2621 are where that gets answered. On a list where the median opening bid is $8,409, an unpriced recurring lien is not a footnote — it is capable of deciding whether a parcel is worth having.
One place the county disagrees with itself
On item 5, the notice says LAND ONLY. The assessor’s record carries $1,176 of structure value on the same parcel.
It is a small number and there are ordinary explanations — a shed or minor improvement that never came off the roll, or a timing difference between the two records. We are flagging it rather than resolving it, because we cannot resolve it from a desk. Our table shows the notice’s wording, since the notice is the document that governs the sale. If you care about that parcel, this is a question for the Assessor.
What the ratio does not tell you
Assessed value is not market value, and in California it is anchored by Proposition 13 to the last change of ownership, adjusted at no more than 2% a year. A parcel that has not sold since the 1980s can be assessed at a fraction of what it would fetch, which makes a low bid-to-assessed ratio look better than it is — or rather, look different than it is. It is a screen, not an appraisal.
Everything the screen cannot see still applies here, and Mariposa’s geography makes several of them live questions: legal and physical access, whether a parcel is buildable, water and septic feasibility, fire hazard severity and what it does to insurance, and the county’s own zoning. A 40-acre block you cannot reach or build on is not a bargain at any ratio.
If you are going
Three days is enough to check a handful of parcels properly, and not enough to check thirteen. The mechanics, from the county’s notice and packet:
- Thursday, August 6, 10:00 a.m., Board of Supervisors’ Room, 5100 Bullion Street, Mariposa. Registration opens 9:00 a.m.
- No pre-registration. Registration form plus a $5,000 cashier’s check payable to “Mariposa County Tax Collector”, handed in on arrival. Guaranteed funds only — cash, cashier’s check or money order. No personal checks.
- Settlement is immediate at the end of the sale. Above $5,000 you may put down $5,000 or 10% of the price, whichever is greater, with the balance due within 30 days. Miss it and the deposit is forfeited to the county general fund.
- Buyer also pays transfer tax of $1.10 per $1,000 plus recording fees, and the 2026/2027 tax bill arrives in October 2026.
- Redemption closes Wednesday, August 5, at close of business. Parcels drop off the list until then.
- Unsold parcels may be re-offered at govease.com or in the same room, at the Tax Collector’s discretion. The notice gives no re-offer date, so do not plan around one.
Verify all of this against the county before you act on it — the notice and the tax sale page are the authority, not us.
Sources
- Mariposa County Tax Collector, Notice of Public Auction on August 6, 2026, signed by Courtney Progner Morrow and executed June 16, 2026 under Board of Supervisors Resolution 2026-260; published in the Mariposa Gazette 7/16, 7/23 and 7/30/2026. Item numbers, APNs, county use labels, minimum bids and the special-assessment marking are read directly from it.
- Mariposa County Tax Sale Information Packet 2026 — registration, deposit, settlement and fee terms.
- Mariposa County assessor parcel layer (
Parcels_with_Value), the county’s own published GIS service — land value, structure value and acreage for all 13 parcels, matched by APN. - California Revenue and Taxation Code §3692 (the authority for the sale), §§4674–4676 (excess proceeds).