Be careful you don't fall off the Obamacare "cliff" when the boss asks you to put in some overtime.

Working more could ultimately mean thousands of dollars less for you under a quirk in the new health-care law going into effect this fall. This could prompt some people to cut back on their hours to avoid losing money.

"Working more can actually leave you worse off," the price-comparison site ValuePenguin.com notes in a new analysis.

"It's sort of an absurd scenario," said Jonathan Wu, ValuePenguin.com's co-founder. "It's something for people to be aware of."

In that scenario, an individual or family whose annual income surpasses maximums set by the federal government—if only by $1—will totally lose subsidies available to buy health insurance under the Affordable Care Act.

(Read more: Obamacare fraud?)



The loss of those subsidies in some cases will mean that people potentially would have been better off financially if they had worked less during the year, Wu said. And they then would have to work significantly more to make up for the lost subsidy.