No one wants to deal with money problems when they get older. But, unfortunately, many high schools and colleges don’t teach teens and 20-somethings how to manage their finances properly. In fact, the average person under 35 has around $5,800 in credit card debt alone, according to ValuePenguin. That’s on top of student loan debt, living costs, and other expenses such as car payments or a mortgage. And although you might think you’re careful with your money by doing things such as setting a budget, there are many smaller financial mistakes you could be making. We reached out to experts to find out some of the most common missteps made in your 20s that can lead to massive debt in your 30s, and how to avoid them.

1. Paying even one bill late

It can be easy to get caught up in life and miss the occasional bill payment. But that innocent act can put you on a bad path. “Missing one payment on any bill can not only lead to interest charges, late fees, and debt, but to poor credit profiles and scores,” said Kevin Gallegos, vice president of Phoenix operations for Freedom Debt Relief. “To avoid, open all mail (paper and electronic) as soon as it arrives.”

An easy way to ensure you’re paying all your bills on time is to set up automatic payments. Most companies offer this as an option. If you’re struggling to pay your bills, look to see where you can cut costs in your lifestyle. Or, if you’re burdened with debt from credit card bills and loans, check out debt consolidation companies and student loan refinancing options.

2. Not thinking about your credit score

A credit score is something that might never cross your mind until it’s time to take out a loan. But that’s when it’s too late. Having a low credit score or no score at all could mean you’re not eligible for the money you need to borrow or that you’ll get stuck with high interest rates you can’t afford. That’s why it’s important to start building a credit history as soon as possible. “You can easily create a strong credit profile that will save you thousands on home and auto loans and insurance,” said Todd Huettner, president of Huettner Capital. “Start with one credit card and put something small on it each month like gas and pay it off each month.”

3. Signing up for subscription services

From movies to groceries, the internet has made it easy to get everything on demand. But that convenience comes at a cost. “The biggest mistake I made in my 20s wasn’t big purchases but the little things that added up like subscription services,” said Catherine Agopcan, founder of personal finance website Sisters for Financial Independence. “Spending a few dollars a month on Netflix and other services was a huge hidden money drain.” Not only should you consider your income and big budget items such as rent, but you should also look at charges you’re putting on your credit or debit card. Spending $10, $20, or $30 here and there can add up to hundreds every month. Cancel or stop spending money on anything that’s not essential.

4. Not contributing to a 401(k)

You might think that retirement is something that’s way too far off to worry about. Incredibly, 69% of millennials aren’t saving for retirement, according to a 2017 survey by Earnest. “One of the single biggest financial mistakes people make especially in their 20s is not contributing to their company 401(k) plan,” said Scott Salaske, investing expert at Firstmetric.

You have the option to contribute to a Roth or traditional 401(k) on your own, but you can up the ante on your contributions if your employer has a matching program. “Sometimes companies match dollar for dollar on a certain percentage of contributions,” added Salaske. That means if you put $100 into your retirement, your company could match a percentage of that. While this financial mistake won’t put you into debt, you could miss out on free money.

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