Yes. A cosigner can sue the primary borrower to recover money the cosigner paid on a defaulted loan. The law treats those payments as a financial burden the borrower was supposed to carry, and it gives you several ways to force reimbursement: a breach of contract claim on the loan itself, an unjust enrichment claim for the benefit the borrower kept, a fraud claim if the borrower lied to get you to cosign, or the doctrine of equitable subrogation, which lets you step into the lender’s shoes and use the lender’s collection rights against the borrower.
Whether the lawsuit is worth filing is a separate question from whether you have the right to file one. The answer to the first is almost always yes. The answer to the second depends on what the borrower actually has to collect.
Why the Law Backs You Up
Contract and equity law have long recognized that a guarantor who covers a principal’s debt is entitled to be paid back. Courts get there two ways. As a surety, you hold a direct right of reimbursement against the borrower for anything you laid out because of their default. Under equitable subrogation, paying the lender transfers the lender’s claims to you, including rights to any collateral if the loan was secured. Subrogation doesn’t hand you more rights than the lender had, but it hands you the same enforcement tools.
These rights exist even without a separate written agreement between you and the borrower. A side agreement makes the case easier to prove, but its absence doesn’t take away your ability to sue.
The Claims You Can Bring
Breach of Contract
The loan agreement is a contract in which the borrower promised to make payments. When they stopped paying and you covered the shortfall, they breached that promise. You don’t need a separate contract between yourself and the borrower to bring this claim, though having one strengthens your position. Proof comes from the loan agreement, records of the borrower’s missed payments, and documentation of the payments you made in their place.
Unjust Enrichment
If the contract theory gets tangled, unjust enrichment is the backup. The borrower received the full benefit of the loan (the car, the tuition, the cash) while you paid for it. Courts evaluating this claim look at whether the borrower received a tangible benefit, whether you suffered a matching loss, and whether letting the borrower keep the benefit without paying you would be inequitable.
Fraudulent Misrepresentation
Fraud applies when the borrower lied to get you to cosign: overstated income, hidden debts, false promises to refinance. The evidence bar is higher. You need to show the borrower knowingly made a false statement, that you relied on it in deciding to cosign, and that the reliance caused your loss. If you prove fraud, punitive damages become possible on top of your actual losses. Fraud also matters later if the borrower files bankruptcy, because debts incurred through fraud are not dischargeable.
What You Can Recover
The core recovery is compensatory damages covering every dollar you paid on the borrower’s behalf: principal, interest, late fees, and collection costs. Your recovery is limited to what you can document, so keep meticulous records of every payment.
Consequential damages may be available if the default caused harm beyond the payments themselves. A cosigner whose credit was tanked by reported delinquencies, and who then paid a higher interest rate on a mortgage or was denied credit outright, may be able to recover those downstream losses if the causal line is clear.
Courts add post-judgment interest to the amount owed, running from the date of judgment until the borrower pays. Federal courts tie the rate to the weekly average one-year Treasury yield at the time of judgment. State rates vary, often falling somewhere between 4% and 10% annually.
Punitive damages are rare and generally reserved for cases involving provable fraud or malicious intent. Most cosigner suits end in compensatory awards only.
Send a Demand Letter First
Before filing anything, send the borrower a formal written demand. The letter should state the amount owed, explain how you calculated it with reference to specific payments, attach supporting documents (payment receipts, the loan agreement), and set a firm deadline. Fourteen to thirty days is standard. Send it by certified mail with return receipt so you can prove it was received.
A demand letter often resolves the dispute without a lawsuit. When it doesn’t, it shows the court you tried to settle before filing, and some jurisdictions require a written demand before certain contract claims can be brought.
Where and When to File
Small Claims or Civil Court
If the amount falls within your local small claims limit, that’s the faster, cheaper route. Small claims caps range from around $2,500 in some states to $25,000 in others. Filing fees are low, procedures are stripped down, and you usually don’t need a lawyer. For larger amounts, you’ll file in regular civil court, where formality goes up and representation becomes practical.
Venue
You generally have to file in the county where the borrower lives. If you and the borrower are in different states and you have a side agreement, check whether it names a venue. Without a venue clause, expect to sue in the borrower’s home state, which raises the cost and complexity of the case.
Statute of Limitations
Every state sets a deadline for breach of contract claims, and missing it kills the case no matter how strong it is. For written contracts, the window commonly runs from three to ten years, with six years typical. Oral contracts have shorter windows. The clock usually starts when the borrower first defaults or when you first make a payment on their behalf. Don’t wait.
How the Case Moves
You file a complaint describing your claims and damages. The court issues a summons that must be served on the borrower, who then has roughly 20 to 30 days to respond. If they ignore it, you can ask for a default judgment. If they answer, both sides exchange evidence in discovery. For a cosigner case, that means the loan agreement, payment records, communications with the borrower about the debt, the demand letter and any response, and credit reports showing the damage. Many cases settle at this stage once the documentation is laid out. If not, the case goes to a judge.
Collecting After You Win
A judgment is a piece of paper saying you’re owed money. It doesn’t move funds on its own. If the borrower doesn’t pay voluntarily, you use enforcement tools.
Wage garnishment is the most common. Federal law caps garnishment for ordinary debts at the lesser of 25% of the borrower’s disposable earnings per pay period or the amount by which their weekly disposable earnings exceed 30 times the federal minimum wage. Some states cap it lower. You file paperwork with the court to have the order directed at the borrower’s employer.
Bank levies let you pull funds directly from the borrower’s account with a court order and their bank information. A judgment lien recorded against the borrower’s real estate means you get paid when the property is sold or refinanced. In federal courts, such liens last up to 20 years and can be renewed once. State lien durations vary.
The reality most cosigners underestimate: if the borrower defaulted because they genuinely have no money, no assets, and no stable income, the judgment may be uncollectible. That’s what courts call “judgment proof.” Assess this honestly before spending time and filing fees on a lawsuit. The legal right to sue is clear. Whether there’s anything to collect is a different question.
If the Borrower Files Bankruptcy
Borrower bankruptcy is the biggest disruption to any recovery plan. The moment a bankruptcy petition is filed, an automatic stay halts every lawsuit, collection action, and enforcement effort against the borrower. A pending case stops. A planned filing has to wait. Violating the stay can result in sanctions against you.
Chapter 13 adds a codebtor stay that generally protects cosigners on consumer debts while the repayment plan is active. That cuts the other way when you’re the one trying to collect from the borrower, because your reimbursement claim is against a debtor whose creditors are now frozen. The court can lift this stay in limited circumstances, such as when the plan doesn’t propose to pay the debt you covered. Chapter 7 has no codebtor stay.
A Chapter 7 discharge wipes out the borrower’s personal liability for most unsecured debts. That discharge protects the borrower, not you, so your own obligation on the underlying loan remains. But your claim against the borrower for reimbursement is itself a general unsecured claim, and in most cases it gets discharged along with the borrower’s other unsecured debts.
The exception is fraud. Debts incurred through fraud are not dischargeable. If the borrower lied about their finances to induce you to cosign, you may be able to argue the reimbursement obligation survives bankruptcy. Plan on hiring an attorney for that fight.
Tax Treatment When You Can’t Recover
If you paid the debt and can’t collect, the IRS may let you claim a nonbusiness bad debt deduction. You must show a genuine debtor-creditor relationship (meaning you expected repayment, not that you made a gift), that the debt is completely worthless (partial write-offs aren’t allowed for nonbusiness debts), and that you took reasonable steps to collect. A lawsuit that went nowhere or the borrower’s bankruptcy satisfies the collection effort requirement. You don’t need a court judgment if you can show that getting one would be futile.
The deduction is reported as a short-term capital loss on Form 8949, regardless of how long the debt was outstanding. Capital losses first offset any capital gains for the year, then up to $3,000 of the remaining loss can reduce ordinary income. Anything left over carries forward. Attach a detailed statement to your return explaining the debt, the borrower, your collection efforts, and why you concluded the debt was worthless. Keep the loan agreement, payment records, demand letter, court filings, and evidence of the borrower’s inability to pay.
Alternatives Worth Trying First
Litigation is expensive and slow. Before filing, check whether the borrower can refinance the loan into their own name, which removes you from the obligation entirely. Some lenders offer formal cosigner release programs once the borrower has a track record of on-time payments and passes an independent credit review.
If refinancing isn’t realistic, a written repayment plan directly between you and the borrower may recover more money over time than a judgment they can’t pay. Mediation is another option that costs a fraction of litigation and sometimes produces an agreement both sides accept. When none of that works, the demand letter followed by a lawsuit is the right escalation. Go in with clear expectations about what a judgment is actually worth given the borrower’s finances.