Students don’t realize how much money college will actually cost. (Julio Cortez/AP Photo)

In a month, high school students nationwide will make the final decision about where they want to go to college.

And then comes the reality.

They’ll realize they don’t have enough money to attend the college of their choice without borrowing — in some cases, heavily.

Students will tap whatever subsidized and unsubsidized federal loans that may be offered. But they are limited in what they can borrow. Their parents can also take out federal parent PLUS loans. But when parents can’t or are unwilling to borrow, increasingly students are turning to grandparents.

My advice: Meemaw, nanna, grandma, Big Mama/Papa, granddad, Pops, don’t do it. Don’t co-sign for a student loan.

Read this from Investopedia: Seniors: Before You Co-sign That Student Loan

“It seems like such a harmless endorsement: Co-signing a student loan for dear, sweet Madison, the apple of your grandmotherly eye,” Anne Mollegen Smith writes. “Of course, you want her to go to college; of course, you’re willing to vouch for her! Too bad you won’t have much spare cash to help her out, now that you’re close to retiring. But it doesn’t take any money out of your pocket to co-sign a loan, so why not give this lovely child the benefit of your excellent credit rating?”

This is why not: If your grandchild can’t or won’t repay the loan, you’ll be fully responsible.

When you co-sign for a student loan, you are not the backup borrower. You are on the line for the entire loan balance should your grandchild not pay.

When seniors default on federal student loans, their Social Security benefits can be docked to repay the debt. As much as 15 percent of your benefit payment can be withheld. If there is a silver lining, it’s this: Your Social Security benefits can’t be dunned for defaulting on private student loans. But the lender can still take you to court to try to collect the amount due.

Read more: Can Student Loan Debt Eat Up Your Social Security Benefits?

“The number of people over 60 struggling with college student loans is snowballing,” reported Gail MarksJarvis for the Chicago Tribune. “For most, the struggle is not a hangover from their own college days. Rather, the strain is coming from helping their children and grandchildren pay for college.”

Read more: The fastest-growing category of student debtors may surprise you: Senior citizens

Older Americans now carry an unprecedented amount of student loan debt into retirement, according to a report released last year by the Consumer Financial Protection Bureau (CFPB). Over the past decade, the number of older student loan borrowers has quadrupled.

In 2015, older consumers owed an estimated $66.7 billion in student loans, the CFPB report said. And although most student loan borrowers are young adults between 18 and 39, folks 60 and older are the fastest growing age-segment of the student loan market.

Read the CFPB report: Snapshot of older consumers and student loan debt

Whether you’re a grandparent or a parent, read this: The alarming consequences of co-signing your child’s student loans

This may help, too: Four tips to help older student loan borrowers navigate common problems with their student loans

Your thoughts
Are you a grandparent or retiree stuck with student loans? Share your story. Send your comments to colorofmoney@washpost.com. In the subject line, put “Student loans.”

Retirement rants and raves
I’m interested in your experiences or concerns about retirement or aging. What do you like about retirement? What came as a surprise?

If you haven’t retired, what concerns you financially? You can rant or rave. This space is yours. It’s a chance for you to express what’s on your mind. Send your comments to colorofmoney@washpost.com. Please include your name, city and state. In the subject line, put “Retirement rants and raves.”

Last week I asked you to weigh in on the increase in divorce among adults 50 and older. The divorce rate has roughly doubled since the 1990s in this demographic, according to a report last year by the Pew Research Center. For people 65 and older, the divorce rate has roughly tripled since 1990. I asked: Did you go through a gray divorce, and what was the impact on your retirement plan?

Merrie Soltis of Atlanta wrote, “My husband walked out on me two weeks before Christmas. I told him as he was leaving ‘We can’t AFFORD this!’ Together, we are financially solid. He earns over $100,000 and I earn less than $40,000. But if I make it another two weeks, we will have been married 10 years so at least I can collect on his Social Security, which will be a big improvement. My biggest concern is retirement, because at my age and income level, there’s no way I’ll be able to build a 401(k). I’m scared and angry. I’ll never be able to afford all the things I wanted to do like travel. I knew my marriage had issues, but I was willing to put up with it rather than be financially devastated. Now I’m worried that I’ll never be able to retire. And right now, everything is in limbo while we’re hashing out a settlement. That’s the worst part: not knowing what I’m facing.”

Andrea is 56 and has been divorced three years after being married for 32 years.

“I have two children in college and a third on his way next year,” she wrote. “My ex was good with retirement, but he was the big earner. He’s pretty good with money with me, but I definitely came out on the bad end of the deal. It wasn’t worth the fight. Because of that, however, he’s good about sharing some bigger children costs. I am scared to death about retirement. I don’t understand enough. I try and try. I watch videos, I read your column (I could weep with happiness about how easy you make things understood — thank you!!!). I try to understand what the right thing to do is. I have retirement money and a little money in stocks, but I can’t understand what to do with it. I have retirement money, maybe $500,000 and I really feel like there is no way I can retire.

Compared with how little others have saved, Andrea has a better retirement cushion than most.

I suggest reading: How to Retire on $500,000 in Your 50’s or 60’s

Jeff R. of Maryland wrote, “Five years ago at age 50, my wife and I separated after 20 years of marriage. Our divorce finalized two years later and left me holding the bag of tax debts and liens (from her self-employment income) and child support for our teenagers. Our entire marriage was living above our means, so I could never save substantially for retirement, other than a small pension from a former employer. I had to take an actuarially reduced amount because of the divorce, so that hurt as much as the divorce itself. Now I will have to work until either my health stops me, or my death. I am saving a little bit toward a 401(k) and an IRA, but I know it won’t be enough with what little time I have left. What is retirement anyway?”

Read more: Best retirement advice for many: Never retire

Amanda Linehan of Boston wrote about what it’s like seeing your parents divorce after decades of marriage.

“I’m in my late 30s and my parents are currently dividing assets at age 70, and it’s been excruciating on myself and my fellow adult sibling,” she wrote. “While they effectively ended their marriage in the 1990s, they have waited until now to formalize the division of their retirement accounts and property, including the home I grew up in. When I came to the line about ‘making sure you find an attorney that specializes in QDROs [qualified domestic relations orders],’ I had to laugh. We live in Boston (not exactly a lawyer desert) and found it almost impossible to find a practicing attorney familiar with these types of orders. After seeking referrals and cold calling firms for months I was finally able to secure an attorney equipped to deal with a QDRO and am now watching as the fees eat into the money my parents were meant to live on. Either the cost of childcare for my four-year-old already making it a struggle to save for my own retirement, I now understand all too well what you’ve talked about in your column for years — the notion of a sandwich generation caring for the old and the young at once. I fear these situations will become more common as Baby Boomers retire, divorce, and find themselves in need of QDRO experts; based on my experience, they are none too easy to come by, and as a society we may be ill equipped for a wave of gray divorces if so.”

If you’re going through a gray divorce, read this: Understanding Divorce and QDRO: Dividing Retirement Assets

Newsletter comments policy
Please note it is my personal policy to identify readers who respond to questions I ask in my newsletters. I find it encourages thoughtful and civil conversation. I want my newsletters to be a safe place to express your opinion. On sensitive matters or upon request, I’m happy to include just your first name and/or last initial. But I prefer not to post anonymous comments (I do make exceptions when I’m asking questions that might reveal sensitive information or cause conflict).

If you’re viewing this post online, sign up to receive Michelle Singletary’s newsletters right into your email box: “Your Retirement” on Mondays and “Personal Finance” on Thursdays.

Read and share Michelle Singletary’s Color of Money Column on Wednesdays and Sundays in The Washington Post. You may also see the column in your local newspaper.

Follow Michelle Singletary on Twitter @SingletaryM and Facebook.