The Roth IRA Mistake Costing Millennials Their Best Shot at a Tax-Free Retirement

The biggest Roth IRA mistake is contributing money without actually investing it. Prostock-studio/ShutterstockMillions of millennials are making the same Roth IRA mistake—and it’s silently costing them hundreds of thousands of dollars in tax-free retirement wealth. The error isn’t failing to open a Roth. Most financially aware millennials have one. The mistake is treating their Roth IRA as a savings account instead of an investment vehicle. The $400,000 Mistake Hiding in Plain SightAccording to a Fidelity Investments analysis, approximately 30 percent of Roth IRA holders under 40 have their entire balance sitting in a default money market or cash position. They’ve made the contribution—which takes discipline—but never selected investments. The money sits there earning 0.01 percent to 0.10 percent while the account holder assumes it’s “invested.” It’s not.The cost of this oversight is staggering. A 30-year-old who contributes $7,000 annually to a Roth IRA (the 2026 limit) for 35 years in a cash position would accumulate approximately $259,000. The same contributions invested in a total stock market index fund averaging 8 percent annual returns would grow to approximately $1.24 million. That’s a $981,000 gap—nearly a million dollars in lost tax-free growth—caused entirely by leaving money uninvested.