Every agent has taken an offer off a buyer who could not close. Somewhere between the accepted offer and the closing table, the money that was supposedly there was not, and the listing goes back on the market thirty days older with a sale history that makes the next buyer nervous.
The proof of funds letter exists to prevent exactly this, and most agents treat it as a checkbox rather than a document worth actually reading. That is a mistake, because the letter itself usually tells you which kind of buyer you are dealing with, if you know what to look at.
What a letter that means something looks like
A credible proof of funds letter is short, specific, and checkable.
- A named source of funds, with a phone number that reaches an actual person, not a general voicemail box
- An amount tied to this transaction, either the specific property or a clearly stated purchase price range
- A recent date, inside the last thirty days
- Plain language that funds are available for this deal, subject to ordinary underwriting and title work
- A signature you can trace back to the letterhead
That is the whole list. Nothing about a proof of funds letter needs to be elaborate to be real. The letters that are hardest to fake are the boring, specific ones, because faking specificity requires knowing details a template generator does not have.
What a worthless letter looks like
You will see these constantly, and they tend to fail in the same handful of ways.
No property, no range, just a big number. "Buyer is qualified up to $800,000" tells you nothing about whether this buyer can close on this house. It is a lead magnet dressed up as evidence.
A phone number nobody answers. If the call rings out or reaches a voicemail that never returns your message, treat the letter as if it does not exist. A real funding source answers calls about live deals, because live deals are its business.
Obviously templated. The same paragraph, the same font choices, circulating under different letterheads. Agents who see volume recognize this instantly.
A promise with no conditions attached. A letter claiming unconditional funding regardless of underwriting or title is not more convincing, it is less. Every real capital source looks at title before wiring money, and a letter pretending otherwise is telling you the writer does not actually fund deals.
A screenshot of a bank balance. These get submitted because they look like hard evidence. They are weaker than a letter: a balance on one day is not a commitment to this purchase, it can be moved the same afternoon, and it exposes the buyer's personal finances to you for no benefit to either of you.
What to do when a letter is thin
Ask for a better one, and do it plainly. "Can you have your lender send something with the property address and a callable number, so I can confirm it before we move forward" is a normal request that any legitimate buyer's lender fields routinely. It does not read as an accusation, and a buyer who gets defensive about a request this ordinary is telling you something.
If the buyer is working with a private lender rather than a bank, the request is the same. A proof of funds letter from a hard money lender should carry the same specifics: this property, this amount, issued recently, with someone reachable behind it. If a buyer cannot get one same day from whoever is actually funding their purchase, that is worth knowing before you take the listing off the market for them.
Verifying without insulting the buyer
The call itself is the least awkward part of this, if you frame it correctly. Every experienced agent confirms proof of funds on cash offers, every time, regardless of how the buyer presents. Say so directly: "This is standard on my end for any cash offer, I'll just confirm with the number on the letter." A buyer whose funds are real has nothing to lose from a thirty-second call, and a buyer who objects to it has usually told you the answer already.
What you are listening for on that call is simple. Does the person answering know this deal, this property, and this buyer, or are they reading from a script that could apply to anyone. A funding source who has actually looked at the deal will reference specifics without prompting.
Where this actually bites a transaction
Rarely at the offer stage. It bites at underwriting, a week or two before closing, when a lender who was shown a vague version of the deal discovers the real numbers do not support the loan. By then your seller has turned down other offers and the listing has lost weeks it will not get back.
The way to avoid inheriting that timeline is to push the verification earlier, not later. A letter obtained by a buyer who genuinely discussed the deal with their lender tends to survive underwriting. A letter obtained in five minutes from a generic template does not, and the earlier you can tell the difference the less it costs your seller.
What this means for an investor buyer specifically
If your buyer is an investor using fix and flip financing or a DSCR loan rather than a bank mortgage, the proof of funds question is not a substitute for understanding their numbers. A letter confirms the money exists. It does not confirm the deal pencils for them at the price on the contract, which is worth knowing before you invest weeks in a buyer whose offer may not survive their own underwriting once they run the 70% rule against the real rehab budget.
The short version
Read the letter for specifics before you read it for reassurance. A named source, a callable number, a recent date, and language tied to this property are what separate evidence from paper. Confirm it with a phone call, frame the call as routine, and you protect your seller without treating a legitimate buyer like a suspect.
If you have an offer in hand and want a second opinion on whether the letter behind it holds up, send it over along with the property and I will tell you plainly what it does and does not establish.