About 3,000 T.J. Maxx assistant managers nationwide will be allowed to join a lawsuit against TJX Cos. for failure to pay overtime, following a federal court ruling this week.

The ruling, in US District Court for Eastern New York, grants conditional certification for a collective action lawsuit, similar to a class-action suit, which was filed in early 2011 by a former assistant manager in New York. The complaint alleges that the Framingham company regularly required Mohammed M. Ahmed and other salaried assistant managers to perform duties usually done by hourly workers, such as running the cash registers and unloading delivery trucks, without paying them overtime when they worked more than 40 hours a week.

“It’s a violation of the Fair Labor Standards Act,” said Sara Kane, who is representing Ahmed.

About 3,000 assistant managers who worked at TJ Maxx from August of 2007 to the present — though the time frame is in dispute — could receive invitations to join the lawsuit.

TJX, which also runs Marshalls and HomeGoods, did not return calls seeking comment.

TJX is facing several lawsuits over similar wage and employee misclassification violations, Kane said.