The consent problem is the heart of it, and it is where these transactions die. In an ordinary sale the seller pays off the loans out of the proceeds and nobody's agreement is needed. In a short sale the proceeds are not enough, so every lienholder is being asked to accept less than it is owed and release its lien anyway. Regulation X's official interpretations put the standard precisely: "an approved short sale transaction is a short sale transaction that has been approved by all relevant parties, including the servicer, other affected lienholders, or insurers, if applicable, and the servicer has received proof of funds or financing."
The list is longer than borrowers expect. The first-mortgage servicer is the obvious party, and behind it the investor that owns the loan and, on an insured loan, the mortgage insurer. Then come the junior lienholders: a second mortgage, a home equity line of credit, a judgment lien, a contractor's lien, unpaid property taxes. A junior lienholder in a short sale is usually being offered a small fraction of its balance, because the first mortgage is not being paid in full and everything below it is out of the money. It can refuse, and its refusal is enough on its own to stop the sale. That is the mechanical reason a homeowner with one mortgage often completes a short sale and a homeowner with two often does not.
Regulation X supplies the machinery, and one part of it is worth knowing because it buys time. Where a servicer is evaluating a borrower for loss mitigation, the official interpretations provide that it "complies with the requirement for evaluating the borrower for a short sale option if the servicer offers the borrower the opportunity to enter into a listing or marketing period agreement," even where the specifics of an acceptable transaction depend on further information from an appraisal or title search. And a borrower "is deemed to be performing under an agreement on a short sale, or other similar loss mitigation option, during the term of a marketing or listing period." That matters because 12 CFR 1024.41(g) bars a servicer from moving for foreclosure judgment or conducting a foreclosure sale while a borrower is performing under a loss mitigation agreement. The marketing period is not just a window to find a buyer; it is a window in which the foreclosure cannot proceed. The interpretations also state the flip side: if the borrower has not obtained an approved short sale by the end of the marketing period, the servicer may treat that as a failure to perform.
What FHA requires, under the framework that took effect on 1 October 2025. Mortgagee Letter 2025-12 replaced the previously published Standard PFS, which expired on 30 September 2025 along with FHA-HAMP and the COVID-19 recovery options. Under the current text, a Standard PFS is available to owner-occupant and non-occupant borrowers, and the mortgagee must ensure that the borrower indicates a financial hardship affecting their ability to sustain the mortgage, that the mortgage is 61 days or more delinquent as of the date of approval, and that the borrower "has exhausted or been deemed ineligible for all permanent Loss Mitigation Home Retention Options." The mortgagee must send form HUD-90035, the pre-foreclosure sale information sheet, and must disclose in writing that the borrower has to keep the property in "ready to show" condition and perform normal maintenance until closing, and that PFS transactions "are reported to consumer reporting agencies and will likely affect the Borrower's ability to obtain another Mortgage and other types of credit." In HUD's loss mitigation waterfall the PFS sits at the last question, after every home retention option has been considered.
Whether the shortfall goes away is the question to settle in writing. HUD's definition says the lienholders "agree to release their liens and forgive the deficiency balance," but that is the FHA program describing itself, not a statement of general law. Outside that program, whether a lender releases the borrower from the remaining balance is a term to be negotiated, and an approval letter that releases the lien without releasing the debt leaves the borrower owing the difference. What happens to that remaining amount, and why it is usually larger than the naive gap between price and payoff, is covered on the deficiency balance page. State law varies considerably on whether and how a lender may pursue a shortfall after a sale, so the reliable move is not to rely on a general rule but to read the approval letter for an express release.
The tax question is separate and has changed. Where a lender does forgive the shortfall, the forgiven amount is generally income unless a statutory exclusion applies, and the exclusion most people have heard of, for qualified principal residence indebtedness, no longer reaches discharges completed after 2025 except under a written arrangement entered into before 2026. The cancellation of debt page states the current position and quotes the Internal Revenue Service's own wording, and it is the page to read before assuming a short sale is tax-free.
Two practical realities. A short sale takes longer than an ordinary sale, often by months, because the price has to be approved by parties who are not at the closing table and who are comparing it against what a foreclosure would recover. And the borrower is selling a house they cannot afford while maintaining it to a standard the program requires, which is a genuine burden during the marketing period rather than a formality.