It might sound silly to think of money you never had as a waste. But it’s true. If you deserve a raise but don’t ask for one, or if you don’t negotiate your salary when you’re deciding whether to accept a new job, you’re losing money.

Three in five workers didn’t negotiate their job offers. Pro tip: You never want to be the first one to give a number. Let the person making the offer tell you the salary range for the position first, then ask to think about it and make a counter offer.

This is especially true for women, who tend to negotiate less than men do. In 2016, women working full time were paid just 80% of what men were paid. Men are 41% more likely to be in management and executive roles, and 20% of women believe gender has contributed to a missed promotion or raise.

If you’re applying for a new job, make sure you’re using your network. Sixty percent of people said they have referred someone for a job, and 35% said they got a job through a referral. This is pretty good news for people who hate cover letters, because 47% of job applicants said they didn’t even submit one to get a job.

If you’re asking for a raise, make sure you’ve got your accomplishments and your accolades in order. Practice what you’re going to say to your boss, bring your research to back your request and be confident.

Bottom line: Money you don’t ask for is money wasted.