The lead came in clean, the investor rewrote the contract before closing, and now the seller is the one asking what happened

The clause that holds is one that ties the fee to the introduction event, not the transaction outcome. Something like "a fee of $X becomes due and payable upon closing of any transaction between investor and seller introduced by bird dog within 24 months of introduction, regardless of price, terms or structure of that transaction" removes the investor's argument entirely, because the closing price is irrelevant once the introduction is the triggering event. The 24-month tail matters as much as the price language, because a renegotiation that stretches three weeks is nothing compared to one that stretches three months with a new contract number on top.

The related piece that changes the picture here is what happens when the fee is a flat dollar amount versus a percentage. A flat fee tied to introduction survives price movement because there is no calculation to dispute. A percentage tied to "offer price" or "agreed price" invites exactly the argument this investor made, and experienced investors know that before they sign. If the original agreement said percentage of offer price, the investor did not rewrite the contract by accident.

What did the original agreement actually say as the triggering condition, the introduction or the closing?

This is a contract drafting question at its core, so I want to flag upfront: the specific language you use in an agreement should be reviewed by a real estate attorney in your state. What I can do is explain how the fee structure works conceptually, so you know what to ask for.

The problem here is that the fee was tied to the deal price rather than the introduction. When a deal renegotiates, a price-tied fee moves with it. The fix is to anchor the fee to the referral event, not the closing number.

Language that does this typically reads something like: "A fee of $X is earned upon introduction of the seller, defined as the investor's first direct contact with the seller, regardless of the price, terms, or structure of any subsequent agreement."

A few things that language needs to do:

Define "introduction" precisely. Name the date, the seller, and the property address. The moment that introduction happened, the fee is earned. What closes after that is a separate matter.

Separate the trigger from the amount. The fee triggers on introduction. The amount can be fixed (a flat $2,000, for example) or calculated from the original submitted offer price, stated explicitly as the price in the bird dog's written lead submission, not the final closing price.

Include a direct-contact clause. This says the investor agrees not to contact the seller directly except through channels the bird dog controls, until the fee agreement is signed. Once they have the seller's number, your leverage is gone.

The thing worth knowing here is that verbal agreements and informal handshakes are how bird dogs get burned most often. The agreement needs to exist in writing before the introduction happens, not after.

What did your original agreement look like? Was anything in writing before you handed over the contact?

The assumption doing the most work in your original agreement was that the deal you introduced would resemble the deal that closed. Once the investor has direct seller access, that assumption breaks.

The fix is in how you define the triggering event. Fees tied to a closing price give the investor a direct financial incentive to renegotiate after the introduction. Fees tied to the introduction itself remove that incentive entirely. The language that holds is something in the structure of: the fee is earned upon introduction of the seller, defined as first contact facilitated by the bird dog, and is payable upon any closing with that seller within a defined period, regardless of the price or terms at which the deal closes. You want a flat fee triggered by the introduction, not a percentage of the closing price. If a percentage structure is preferred by your investor clients, tie it to the original offer price as a floor, not the final closing price.

Two other clauses matter. A non-circumvention provision that names the seller specifically and prohibits direct negotiation without the bird dog's involvement at least gives you a contractual basis if the investor routes around you. A time window matters too, since without one an investor can let a deal go cold, wait out the clock, and re-approach the seller independently.

A licensed attorney needs to draft or review whatever agreement you use. That is not a formality here. Finder's fee arrangements sit in state-regulated territory, and some states have restrictions on how non-licensed parties can be compensated in real estate transactions. Get that reviewed before the next deal, in writing, with someone who knows your state's licensing rules.

The practical shift for your operation is moving toward flat introduction fees wherever your investor clients will accept them, which frames the value correctly: you found the seller, not the final price.

What does your current agreement actually say the fee is triggered by?