Photo: Christian Scholz/ Flickr

Today marks the official beginning of what may go down as the most underappreciated action of Obama’s presidency: the new overtime rule, which will force more money into the pocket of the middle class.

The Department of Labor has officially issued its new overtime rule, which has been the subject of fierce negotiations for years. It goes into effect on December 1. Quite simply, it will raise the threshold for getting overtime pay to $47,476 a year, which means that even if you are a salaried worker, you are entitled to overtime pay if you make less than that amount. (Overtime pay was standard for Americans a generation ago, but the threshold had been allowed to remain at $23,660 for more than a decade, making it out of reach for virtually the entire middle class.) According to the Economic Policy Institute, more than 12 million workers will be newly eligible for overtime as a result of this rule change, including a disproportionate number of black, Latino, and female workers.

In essence, if you make a lower middle class salary, your boss can no longer classify you as a “manager” and then have you work a huge number of hours for no extra pay. No matter what businesses do to try to get around this rule—and their options are fairly limited—this will increase pay for millions and millions of workers. That’s a big deal.

Start keeping track of your hours now. Don’t expect your boss to do it for you. And look up employment lawyers, if you need to.