There are two things most everyone can't avoid in life: death and taxes. But if you're a parent, you've got a third: managing the significant expenses of child rearing.

Should your child -- or children -- choose to pursue a college degree, those expenses can get even bigger. According to the College Board, the average cost of tuition and fees for the 2017-2018 school year was $34,740 at private colleges, $9,970 for state residents and public colleges and $25,620 for out-of-state residents at public colleges.

While kids should be encouraged to save for their own education, it's unrealistic to assume that as a parent you won't have to help out here and there.

According to a study from Student Loan Hero, 74% of parents are using a savings account for college funds. But also among those polled, nearly 40% of parents still had student loan debt of their own.

But the most staggering takeaway is that parents saving for college could sacrifice their own retirement savings to make ends meet after high school graduation rolls around. Student Loan Hero found that although 44% of parents prioritize saving for retirement over saving for college costs, a significant 37% of parents said no savings goal is more important than their kids' education.

But that priority could come with an unexpected side effect. About 37% of parents said they've already considered borrowing from their retirement savings to pay for college. Roughly 18% of parents said they were unsure if they would have to dip into retirement accounts by the time their kids go to college.

Here's why that's a bad idea for both you and your kids. Dipping into your 401(K) before you reach the age of 59 means whatever you withdraw could be subject to a hefty 10% fee plus income taxes.

So how do you help the kids pay for the best four years of their lives without sacrificing the twilight years of yours?

The first -- and best -- step is to apply for financial aid from the college of choice. According to U.S. News, the average aid package is $29,916 for a school where tuition, room and board total $40,580. That's no small discount.

Make sure your kid is also applying for relevant scholarships and grants from both the school and local organizations. Encourage your child to apply for a work-study program, too.

If you do need to take out a loan, consider the smartest option: a federal loan, the loan type that 52% of parents expect to use in taking out money to help with college costs. Federal loans come with payment protections and parents can lower monthly payments.

Avoid using a credit card to pay for college like 16% of parents expect to do. Credit cards often carry a higher interest rate than federal loans. Plus, of the roughly 60% of colleges that accept credit card payments, many charge a convenience fee of about 2.6%.

Finally, remember -- being an empty nester can be hard. But being an empty nester with nothing in the way of retirement savings is even worse.

TheStreet's Robert Powell is America's preeminent expert on retirement. Catch one of his latest podcasts on retirement planning below.