Originally posted by Nancy Anderson on https://www.forbes.com

Any wise financial planner knows to get a second opinion on her own retirement plan. So I wasn’t surprised when a 30-year-old colleague asked me to be her second look, and I gave her my opinion freely.

As you’d expect from a Certified Financial Planner ™ professional, she had her basics down. She had an emergency fund with six months of her net income, no credit card debt, and she was on track to replace her income in retirement. In fact, at the rate she is going, she will replace over 100% of her income in retirement. When I reflected on our meeting later, I wondered why more 30-year-olds aren’t as prepared as she is.

But then I realized that she is in the industry, and is not making a lot of false assumptions that other younger people make. Decisions based on the wrong information can lead to costly mistakes, and the results could be as serious as having to delay retirement or living on a reduced income later.

Here are four false assumptions that a lot of people in their 30s make—and ways to help them to stay on the right track for retirement.

1. They assume it will be easier to save in the future. The truth is that your 30s can be an expensive decade. Many people are establishing a household, having children and buying a home, along with all the furnishings that go in it. So it may actually be more difficult to save in your 30s than in your 20s. My colleague started saving the absolute maximum she could in her late 20s, knowing that she wanted a house and family someday. She figured, correctly, that even though her income might grow exponentially in her 30s, her expenses might surpass her income.

Tip for 30-somethings: Seriously consider maximizing retirement savings earlier in your career, knowing that you may have gaps in savings in the future.

2. They don’t verify that they are on track for their retirement goals. My colleague runs her own retirement calculations all the time. She wanted a second set of eyes to see what she might be missing, as well as some high-level strategies. According to recent research from BlackRock BLK +1%, more than 4 in 10 people surveyed weren’t saving because they hadn’t run retirement calculations and didn’t know how much they needed to save. But almost 8 in 10 said they would start saving or increase their contributions if they knew how much they needed to save. Since the new model of retirement planning consists of employees managing their own retirement with a defined contribution plan, it’s important to be proactive.

Tip for 30-somethings: At a minimum, run a retirement calculation. Some calculators to get you started and here and here.  Meeting with a Certified Financial Planner ™ professional can be one way to get started on your financial plan. Some resources that can help include Let’s Make a Plan andLearnVest (use discount code Retire50).

3. They assume the 401(k) is the “be all, end all.” There are major benefits to investing in an employer’s retirement plan. First of all, you can never underestimate the value of automatically deducting funds from a checking account. When funds are invested before ever hitting your bank account, you simply can’t spend that money.  And company-matching contributions are obviously a significant benefit. Employees who receive a company match should invest at least up to the matching contributions in their 401(k).

But don’t ignore the Roth IRA. The tax-free retirement benefit of the Roth is well known, but many folks may not realize how much flexibility the Roth has. The principal amount can be withdrawn for any reason and at any time, without a tax penalty. This serves as a back-up emergency fund, but also gives an investor flexibility to reinvest the principal into something else, such as a down payment on a primary residence or on an investment property. For someone in his or her 30s, a Roth IRA can be the best of both worlds: Investing for retirement and having some flexibility to withdraw the principal without hefty taxes. (A Roth investment is post-tax; meanwhile, a 401(k) carries a 10% early withdrawal penalty.)

Tip for 30-somethings: It can be wise to invest in the 401(k) up to the amount matched by your company. Over and above the company match, consider investing in a Roth IRA.

4. They assume all funds are created equal.  Albert Einstein is rumored to have said that compound interest is the most powerful force in the universe. Compounding fees, on the other hand, are another story. When you pay high annual fees on the funds in your retirement accounts, the compounding works against you. For example, an investor with a $50,000 balance who pays 1.5% in annual investment fees on an account that earns 7% annually would pay about $138,000 in total expenses over 30 years, including opportunity costs. Everything else being equal, that same investment with fees at 0.5% would only incur about $53,000 in total expenses and opportunity costs. Something as seemingly insignificant as a 1% difference in annual fees can add up to an $85,000 difference over time.

Tip for 30-somethings: Think about investing in low-fee mutual funds or index funds in your 401(k).  See your fund’s prospectus for full disclosure on fees. Click here to see how expenses impact mutual fund returns, as calculated by calcxml.com.

Albert Einstein also said that anyone who has never made a mistake has never tried anything new. But frankly, in terms of retirement planning, it’s better to start off strong by not making mistakes in the first place. If you really want to try something new, there’s always hang gliding.