Even Olivia Munn couldn’t get this one comped.

The “X-Men” actress was excited to make a cameo appearance on “Ocean’s Eight,” an all-female spinoff of the “Ocean” heist trilogy. So she didn’t blink an eye when producers asked her to foot her wardrobe and makeup bill up front for a scene set at the ultra-exclusive Met Gala in New York. But when the 37-year-old star submitted her receipts, producers of the blockbuster featuring A-listers like Sandra Bullock, Cate Blanchett, Anne Hathaway and Rihanna told her that the check was her responsibility.

“They’re like, ‘Oh no, the bills come right back to you,’” Munn told Entertainment Weekly Radio in an interview. But she doesn’t seem to really mind. She’s “just as excited about it as everybody else,” Munn added.

The half-Asian actress certainly knows how to pick her opportunities—even when if it means an initial financial hit. In 2010, Munn took an 80% pay cut to join Jon Stewart’s “The Daily Show” as a correspondent. The move paid off: she’s since gone on to roles in “Zoolander 2,” two “X-Men” flicks and a guest judging post on “Project Runway.”

Negotiating such trade offs aren’t just the domain of up-and-coming actresses. They can also include debating asking your employer to chip in for a conference ticket or other expenses that blur the line between business and personal growth and pleasure.

One important thing to do is to keep an eye out on what your colleagues and competitors regard as normal business expenses.“If you’re working with a client and you need to fly to meet them, they should be paying,” says Foram Sheth, careers coach at Ama La Vida.

Additionally, your boss should cover the entire expense if they expect you to attend a course regarding subject matter you’re already familiar with. “It’s not appropriate to pay out of pocket when it’s expertise you already have,” she says. And you don’t need to think too deeply about this: “When you don’t feel valued for your time, you inherently know when that’s the case.”

But just because you can expense something doesn’t mean you shouldn’t be thrifty. When Sheth was a business consultant flying out to meet clients, she was tempted to charge them for a business class ticket but didn’t do so. “You need to weigh if it’s a must have or just a convenience to you,” she says. “I could still get there on economy and it didn’t hamper me.”

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The industry you’re in also matters. Take for instance clothing expenses, which may or may not be seen as a frivolous factor. According to Kristina Leonardi, a New York management coach, it’s probably ok for a TV anchor to insist their station pay for their wardrobe. The same goes if you’re required to wear a uniform, though an investment banker would probably have to pay for a clothing upgrade out of pocket.

Of course, there’s nothing wrong with investing in yourself even if your employer won’t do so. This can mean attending golfing clubs on your own dime so you can better network with clients, or buying that fancy suit to make a sharper first impression. “You’re not doing these particularly to enrich your own life, but rather with a career goal in mind,” says Leonardi, the author of “Personal Growth Gab.” “That’s the case if you want to move up and for people to see you more as an executive. It may help you get access to folks you otherwise wouldn’t have.”

The takeaway: “Always ask if it’s an investment in yourself or if you’re being taken advantage of,” says Leonardi. “If you’re getting something out of it, there’s nothing wrong with paying” out of your own pocket.