N.M. Stat. § 45-3-811
Counterclaims.
A. In allowing a claim, the personal representative may deduct any counterclaim
which the estate has against the claimant.
B. In determining a claim against an estate the district court shall reduce the amount
allowed by the amount of any counterclaims and, if the counterclaims exceed the claim,
render a judgment against the claimant in the amount of the excess.