# Whose Money Is It, and Can You Prove It: Verifying Gift Funds and Down-Payment Assistance With an AI Agent Under Fannie B3-4.3-04

*October 27, 2026 · 6 min read · Ramkumar Venkataraman*

> A gift toward the down payment is the one place in asset verification where the paper trail and the relationship both have to hold, and where the sourcing question quietly becomes a Bank Secrecy Act question. How we build an agent that documents the donor, the transfer, and the availability of funds, tells a personal gift apart from a gift of equity and a DPA second, and knows the exact point at which it stops verifying and escalates to a human.

## The Document Set That Looks Simple and Is Not

A down-payment gift is the friendliest-looking item in a loan file and one of the easiest to get wrong. A parent gives a first-time buyer the money to close, the file gets a gift letter and a deposit, and everyone treats it as done. It is not done, because the gift carries three separate obligations that have nothing to do with the letter, and a file that satisfies the letter while missing the other three is a file that passes a quick read and fails a reverification.

[Fannie Mae's B3-4.3-04 on personal gifts](https://selling-guide.fanniemae.com/sel/b3-4.3-04/personal-gifts) sets the standard, and the standard is specific about what the lender has to establish. The donor has to be an acceptable donor, usually a relative or, on some transactions, a fiancé, fiancée, or domestic partner, and never a party with an interest in the sale such as the builder, developer, or agent. The gift has to be evidenced by a letter signed by the donor that states the dollar amount, the date of the transfer, the donor's name, address, and relationship to the borrower, and that no repayment is expected. And the lender has to verify two things about the money itself: that the donor actually had it, and that it actually moved. Those last two are where the quick reads fail.

## The Transfer Trail Is the Verification, Not the Letter

The letter is a representation. The transfer trail is the proof, and the two are not interchangeable. B3-4.3-04 requires the lender to document the transfer of the gift funds, and it gives a hierarchy of how, from a copy of the donor's check and the borrower's deposit slip, to a wire confirmation, to a withdrawal document from the donor's account paired with the deposit into the borrower's. The underlying requirement is that you can follow the money from the donor's hand to the borrower's account and tie the amount that moved to the amount in the letter. A gift letter sitting next to a deposit of a different amount, or a deposit with no visible origin, is not a documented gift. It is an unsourced deposit with a letter attached.

This is the part an agent is genuinely good at, because it is a reconciliation problem with a paper trail, and it is the same discipline we apply to the [large-deposit question in asset verification](/blog/verification-of-assets-large-deposit-sourcing-ai-underwriting-fannie-bsa). The agent reads the donor's statement or withdrawal evidence, reads the borrower's deposit, matches the amount and the timing, and confirms the chain is unbroken. Where the chain breaks, where the deposit is larger than the gift, where the donor's withdrawal does not appear, where the funds landed before the letter was dated, the agent does not paper over the gap. It names the specific missing link and generates the condition that asks for exactly the document that would close it, which is the same [conditions discipline](/blog/ai-loan-processing-conditions-clearing-los-reg-b-incompleteness) we run across the rest of the file.

## Three Things Called "Gift" That Are Not the Same Thing

The word "gift" hides three different transactions with three different rule sets, and an agent that treats them as one will deliver the wrong loan. A personal gift under B3-4.3-04 is cash from an acceptable donor. A [gift of equity under B3-4.3-05](https://selling-guide.fanniemae.com/sel/b3-4.3-05/gifts-equity) is not cash at all. It is the seller, who has to be a relative or, in defined cases, a related party, selling the property for less than its market value and gifting the difference as equity, which changes the sales-price-to-value math and carries its own documentation and its own restriction that the gifted equity cannot count toward financial reserves.

Down-payment assistance is the third, and it is the one most often misfiled. A DPA program, whether a municipal grant, a housing-finance-agency second, or a lender contribution, runs under [B3-4.3-06 on grants and lender contributions](https://selling-guide.fanniemae.com/sel/b3-4.3-06/grants-and-lender-contributions) and frequently involves a repayable or forgivable second lien, which is a debt, not a gift, and which has to be disclosed, underwritten, and reflected in the combined loan-to-value. A DPA second treated as a gift is an undisclosed lien and a misstated CLTV, which is exactly the kind of defect that surfaces at reverification or, worse, at an investor review. The agent's first job on any "gift" is classification, because every downstream rule depends on which of the three this actually is, and the classification has to be driven by the documents in the file rather than by the label someone typed into the loan origination system. We built the [document classification layer](/blog/mortgage-document-classification-extraction-ai-model-governance-confidence-thresholds) precisely so the thing that decides what a document is governed as carefully as the thing that acts on it.

## Where Sourcing Quietly Becomes a Bank Secrecy Act Question

Here is the part that most gift-funds checklists do not mention and that an agent has to be built to notice. Verifying a gift is an asset-sourcing exercise, and asset sourcing is where mortgage underwriting brushes up against the Bank Secrecy Act. A large gift that arrives as a cash deposit the donor cannot document, a gift that traces back through a series of transfers to an origin nobody can explain, a donor whose stated capacity to make the gift does not match the money that appeared, these are not only Fannie documentation gaps. They are patterns that, in the right fact pattern, raise the kind of question a financial institution has obligations around.

The agent is not a BSA officer, and it does not decide whether anything here is reportable. That line matters, and it is the same line we drew in the [asset-verification and BSA post](/blog/verification-of-assets-large-deposit-sourcing-ai-underwriting-fannie-bsa): an AI agent can surface a red flag, and it cannot make the suspicious-activity determination, because that is a human judgment with a legal consequence. What the agent does is recognize when a gift's sourcing has crossed from "needs another bank statement" into "this does not add up in a way a person should look at," and route it to the named human with the specific anomaly described and the documents that produced it. The failure mode we design against is the agent that quietly clears an unusual gift because the letter was present and the amount matched, when the thing that should have happened was a human looking at why the money existed at all.

## The Reasonableness Call the Agent Does Not Own

There is a judgment inside gift verification that an agent should not make, and building the agent well means being precise about where it is. The documentation is mechanical: is there a letter, does it say what it has to say, is the donor acceptable, does the transfer trail reconcile, is the donor's ability to give the money evidenced. An agent can do all of that at full coverage and do it consistently, which is better than a human doing it on file four hundred of a long week.

What an agent should not do is decide that an otherwise-unverifiable gift is fine because the story is plausible. When the donor cannot document the source of the gifted funds, when the relationship is the kind the rule questions, when the transfer trail has a gap that the available documents cannot close, the right outcome is not an agent that reasons its way to a clear. It is an agent that stops at its confidence floor and hands a named underwriter the exact question, the documents gathered so far, and what is missing. This is the [bounded-autonomy discipline](/blog/long-horizon-agents-vs-copilot-mortgage-bounded-autonomy-sr-11-7) applied to a specific desk: the agent clears the files that are cleanly documentable, surfaces the ones that are not as named exceptions, and never manufactures a conclusion the evidence does not support. The underwriter still owns the reasonableness call, which is where it belongs, because it is the call with the rep-and-warrant consequence.

## Why This Desk Is Governed Like a Model

The policy that decides when a gift is sufficiently documented, when a deposit needs sourcing, and when an anomaly escalates is a set of rules producing a consequential underwriting decision at volume, which makes it something we govern in the spirit of [SR 11-7](/blog/model-risk-management-ai-agents-sr-11-7-nist-rmf). The gift-verification policy has an owner and a version, so when Fannie revises B3-4.3-04, and the gift sections do get revised, the change is applied deliberately and consistently to every file dated after its effective date rather than drifting across whoever happens to be reviewing that day.

The agent also never acts on a rule it cannot cite. When it conditions a file for a missing transfer document, the condition points at the specific guide requirement that the document satisfies, so the underwriter who reviews the exception sees not only what is missing but why the rule wants it. That is the [grounding discipline](/blog/preventing-ai-hallucinations-banking-grounding-citation-architecture) we apply everywhere an agent asserts a requirement: the requirement comes from the Rulebook, with an effective date, and the citation travels with the decision into the record.

## The Honest Read

A down-payment gift is a small item that carries a large share of the file's integrity, because it is where the money a borrower is bringing to the table either has a provable origin or does not, and where an unprovable origin is sometimes more than a documentation gap. The letter is the easy part. The transfer trail, the donor's capacity, the classification of what the "gift" actually is, and the recognition of when sourcing has become a question for a human, those are the parts that separate a file that holds at reverification from one that does not.

We built the asset and gift-verification desk at Sei to do the mechanical reconciliation at full coverage and to stop cleanly at the judgments it should not make, because the point of putting an agent on this work is not to make the hard calls faster. It is to make the easy calls consistent, document them to a standard that survives an investor review, and route the hard calls to a person with everything they need to make them. Whose money is it, and can you prove it, is a question the file should be able to answer on its own, every time, and it is the agent's job to make sure it can.

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_Source: [https://www.seiright.com/blog/gift-funds-down-payment-assistance-verification-ai-underwriting-fannie-b3-4-3-04-bsa](https://www.seiright.com/blog/gift-funds-down-payment-assistance-verification-ai-underwriting-fannie-b3-4-3-04-bsa) · Sei AI_