As a Plaintiff in a Civil Action, am I Entitled to Prejudgment Interest if I Win?
By statute, the clerk in any case is required to add interest to any judgment or verdict issued by a Massachusetts state court. For contract actions (G.L. c. 231, §6C), the rate of interest is either the interest rate in the contract or, if the contract does not have one (or the contract is oral), the rate of 12%. Interest runs from the date of the breach or demand, if it is established, or from the date the complaint is filed. So it is important in a contract case to put in evidence of the date of the breach or demand, as it will be earlier than the date of filing.
For personal injury claims or claims for property damage, the rate of interest also is 12%, and runs from the date of filing of the complaint (G.L. c. 231, §6B). There is also a catch-all interest statute, (G.L. c. 231, §6H), which applies to any damages award on which interest is not otherwise provided by law, at 12% from the date of filing. The SJC recently held, however, that this catch-all statute only applies to an award of compensatory damages. Governo Law Firm LLC v. Bergeron, 487 Mass. 188 (2021). So interest was not added to an award based on the disgorgement of profits from the defendant. Interest would be added to an award based on lost profits of the plaintiff.
These statutes apply in federal court where jurisdiction is based on diversity of citizenship. These statutes do not apply to claims against the Commonwealth. Interest is added, but at the US Treasury Rate up to a maximum of 10% (G.L. c. 231, §6I). The prejudgment interest does not compound annually. However, once a judgment is entered, post-judgment interest runs at 12% on the judgment, inclusive of the prejudgment interest.