A landlord backing out is a breach of contract, not a formality
Signing a lease creates a binding agreement, and that runs both ways. A landlord who cancels after both sides sign — because they got a better offer, decided to sell, or simply changed their mind — is generally breaking the contract, the same as if you skipped out after signing. Move-in day hasn't happened yet, but the contract already has.
Reasons a landlord might have a legitimate out
Some situations give a landlord a real basis to cancel: the unit is destroyed or becomes unsafe to occupy (fire, flood, a failed inspection), a contingency written into the lease itself wasn't met, or you provided false information on your application that the lease made a condition of tenancy. Outside of those, "I found a better tenant" or "I changed my mind about renting it out" is not a legal excuse.
What you're entitled to
At minimum, you should get back every dollar you paid toward that unit — deposit, first month's rent, any holding fee or application cost. Depending on your state's contract law, you may also be able to recover the actual, documented costs the cancellation caused you: a moving truck you already booked, a short-term hotel stay if you'd already given notice at your old place, or the cost difference if you have to rent a comparable unit for more money. These are the kind of damages available for breach of contract generally, but they must be reasonable and documented — keep every receipt.
A concrete example
Say your lease was $1,600 a month starting the 1st, and your landlord tells you on the 25th — five days before move-in — that they've decided to sell the building and won't honor the lease. If you'd already given 30 days' notice at your old apartment and booked a $400 moving truck for the 1st, those are real, documented costs the cancellation caused you. If the only comparable unit you can find on short notice is $1,900 a month, the $300 monthly difference for as long as it takes you to find something at your old price point is also the kind of loss recognized in a breach-of-contract claim — though you'd typically need to actually secure that replacement unit and show the price gap, not just estimate one.
Don't accept a verbal apology as the resolution
A landlord who cancels informally — a phone call, a text saying "sorry, it fell through" — may hope the matter ends there. It doesn't, unless you're made whole. Insist on getting the cancellation and the refund amount in writing, and don't sign anything, like a release or a "mutual agreement to rescind," without understanding exactly what you're giving up by signing it.
What to do right away
Get the cancellation in writing if it wasn't already, and ask the landlord in writing for a full refund of everything you paid. If you already gave notice at your current place or lined up movers based on this lease, tell the landlord in writing what that's costing you and ask them to cover it. If they refuse, small claims court is designed for exactly this kind of dispute and doesn't usually require a lawyer.
If you already gave up your old place
This is the highest-stakes version of this problem — you may be facing a gap with nowhere to live. Document everything (the signed lease, the cancellation, your other housing costs) and start looking for a new unit immediately; the paper trail is what supports a claim for your actual losses later. Don't wait on the landlord's response before you start solving the housing problem.
Before you're in this position again
A lease is only as good as both parties' willingness to honor it, and you can't fully insure against a landlord who won't. What you can do is keep every piece of paperwork from the moment you sign, and move quickly if something goes wrong instead of assuming it will resolve itself. If you're trying to sort out what a lease actually obligated your landlord to do, Honestkey™ can read an uploaded lease and flag the clauses that matter, though it can't predict how a specific dispute will turn out — that's a question for a tenant attorney or your local legal aid office.