How BidDeed Calculates a Max Bid for a Florida Foreclosure Auction

Walking into a Florida foreclosure or tax deed auction without a hard number in your head is how good deals turn into bad ones. The property doesn't care what it's "worth" — it cares what the courthouse steps sell it for that morning, and if your number is soft, you'll bid past it the moment the room gets competitive.

BidDeed sets that number with the SIGNAL$ Max Bid, the formula we used to call the Shapira formula. It is not a fixed percentage of after-repair value. It is learned from what Florida auctions actually sold for, county by county, and it is checked against sales it has never seen before we publish it. Here is how it is built.

The formula

SIGNAL$ Max Bid = Assessed value × County bid share × Plaintiff factor − Recorded liens that can survive the sale, kept inside the county's own floor and cap.

• Assessed value — the county property appraiser's value on the Florida Department of Revenue roll, the same figure the report prints in section 1. If a parcel has no usable assessed value, the report says so and uses its value estimate instead.
• County bid share — learned from completed third-party sales in the same county, with the same sale type and property type: what winning bidders actually paid as a share of assessed value. Every county and sale type has its own fit, and one county's fit is never borrowed for another.
• Plaintiff factor — on a foreclosure, the plaintiff's own track record: what its past sales brought, in cents on the dollar, against the final judgment.
• Floor and cap — the same sales give a low and a high bound. If the result falls outside its own range, the fit is rejected and no number is published from it.
• Recorded liens that can survive the sale — the amounts stated on the record for instruments held by the government bodies Florida law names for a tax deed sale, or recorded ahead of the mortgage being foreclosed, come off the number. An instrument with no amount on the record turns a BID into REVIEW rather than being guessed.

The machine learning behind it

Two predictions sit next to the formula, both trained on prior Florida auction results: the probability that a third party, not the plaintiff, buys at the sale, and the price the sale is likely to clear at, given as a low, middle and high estimate.

For each prediction and each sale type we train five model families — XGBoost, LightGBM, CatBoost, random forest and a regularized linear model — and test each one on later sales it was not trained on. A model that does not beat a simple baseline is dropped. The models are blended only when the blend beats every single model. The sale probability decides whether a strong number reads BID or REVIEW; it never shrinks the dollar figure itself.

Why the report shows it as Withheld today

A max bid is only worth trusting if it has been graded against real outcomes. Until the models pass that test for each sale type, the SIGNAL$ Property Report prints the SIGNAL$ Max Bid, the verdict and the grade as Withheld - validation in progress. The rest of the report — the county record, comps, recorded liens and zoning — is there now, with a source on every figure.

What you still check yourself

Liens and title. Not every lien is wiped out by the sale. The formula subtracts the amounts that are on the record; a lien with no amount on the record, or a title defect, still needs a title professional before you bid.

Tax certificate status. Delinquent taxes and outstanding certificates don't disappear because a property changes hands. Check status before you bid, not after you win.

Occupancy and condition. A property with someone still living in it is a different timeline and a different cost than a vacant one, and assessed value says nothing about the roof.

Flood zone. It affects insurance, resale and your carrying cost, and it is knowable before auction day.

A real example: Marion County, July 2026

Case 422021CA000414CAAXXX, Marion County — a property at 14470 SE 91st Ter, Summerfield, FL.

• Entry bid: $72,100
• Actual sale price: $73,501

The sale closed at $73,501 — $1,401 over the entry bid — and the buyer walked away with roughly $26,400 in day-one equity. Verified against the Marion County courthouse record.

The point isn't that every auction goes this cleanly — plenty don't. The point is that having a number before you're standing in the room, and sticking to it, is what turns foreclosure investing from gambling into a process.

Before you bid, at minimum

1. Pull the case number and confirm it's still active — auctions cancel and reschedule constantly.
2. Check the recorded liens and mortgages that could survive the sale.
3. Confirm tax certificate status.
4. Get a real repair estimate, not a drive-by guess.
5. Look up the plaintiff's past sales in that county, and how far above or below the judgment they cleared.
6. Write your max bid down before auction day. Don't recalculate it live in the room.

This is general educational information, not legal, financial, or investment advice. Auction data and value estimates should always be independently verified. Consult a licensed Florida attorney and title professional before bidding on any property.