Suing a Former Cohabitant for Unpaid Household Bills

Attorney Answer

Yes — $380 in shared bills is a normal small civil claim, and his threat to sue you back is not a reason to hold off. It just means both claims get decided in one case.

New Mexico has no court called "small claims." The forum is the magistrate court. Under NMSA 1978, § 35-3-3, magistrates have civil jurisdiction where the debt or sum claimed does not exceed $10,000, exclusive of interest and costs, covering actions in contract, quasi-contract, and tort. A $380 claim for shared household expenses sits well inside that. In Bernalillo County the equivalent forum is the metropolitan court, whose civil jurisdiction is set at the same $10,000 by NMSA 1978, § 34-8A-3.

What you have to prove is that he agreed to pay — an agreement between people living together does not have to be written, but you do have to show it. Texts, a Venmo history, the account in his name, a pattern of him paying half every month: that is what makes the case.

The dog is a separate question. Courts treat pets as personal property, so ownership turns on records: who bought the animal, who is on the adoption or purchase paperwork, who paid the vet, and whose name is on the microchip registration.

What you can do

1. Pull the bills together and mark exactly what the $380 covers and whose name the accounts are in. 2. Save every text or message where he acknowledged owing it or agreed to split expenses. Screenshot them with dates. 3. Send one short written demand — the amount, what it is for, and a date by which you want payment. Keep a copy. 4. File in the magistrate court in your county (metropolitan court if you are in Bernalillo County). The clerk has the forms and can tell you the filing fee. 5. If he files against you first, bring your $380 in as a counterclaim in that same case instead of starting a second one. 6. Gather the dog records now — purchase or adoption papers, vet invoices, microchip registration — so that issue does not turn into his word against yours.