When offered a pay raise at work, most people won't turn it down. Yet a new Charles Schwab survey finds that three out of every four people don't pick up the full company match in their company's retirement savings plan. And that's effectively like turning down free money!

About half of all Americans work at a place where there's a retirement savings plan like a 401(k). Many employers will even match your contributions, maybe dollar for dollar on the first 3% or 5%, or 50 cents on the dollar up to 6 percent, as just two examples.

That match is the equivalent of an automatic pay raise. No need to ask your boss, get a good quarterly review or hope your company has a good year so there's money for a raise!

Shockingly, though, 75% of people do not put in enough money to get the full match from an employer. If you are among those people, I would love for you to go through a re-evaluation in your own head.

Tell yourself, "I'm doing a good job, so I deserve a raise. And my employer will just nod and agree!" Then simply change your contribution rate -- either during open enrollment or any other time when you're allowed to -- to pick up the full company match.

The most common rationale for turning down free money is, "I can't afford to save any of my paycheck because…" Yet the reality is that except for those living below the poverty line, the way we spend at least a portion of our money is really a matter of choice. There are always things we do with money that are discretionary.

So why not change your discretionary spending habits so you can invest in yourself and get an automatic pay raise?!