For middle-class Americans, who often pay more than they need to simply because they overlook key planning opportunities, small tax decisions can make a big impact. Many taxpayers assume tax planning is only for high earners or business owners, but even tiny missteps involving retirement accounts, side income, tax credits and deductions can quietly cost households thousands of dollars each year.
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The biggest tax errors usually aren’t about cheating the system, but rather they’re about missed strategies, misunderstood rules and filing decisions that seem minor but have long-term consequences. According to tax experts, here are the costliest mistakes middle-class taxpayers make on their taxes.
Overlooking Retirement Account Opportunities
“Middle-class entrepreneurs often overlook retirement account opportunities, which can mean missing out ontax benefits,” explained Nauman Poonja, CEO of Accounovation. “For example, if you make $120,000, you can steer up to $23,000 into a Solo 401(k) and more than $50,000 total across all tax-advantaged accounts.”
To avoid these traps, Poonja recommended having separate business accounts, setting aside 30% for taxes, working with a certified public accountant (CPA) who knows what they’re doing and opening retirement accounts as soon as possible.
Adam Bergman, self-directed retirement expert and founder of IRA Financial, also sees middle-class taxpayers failing to take advantage of Roth IRA opportunities.
“A Roth IRA is one of the most powerful tools for building tax-free wealth in retirement,” Bergman explained. “Since your contributions are made with after-tax dollars, your investments grow without tax and you won’t owe taxes on qualified withdrawals in retirement.”
According to Bergman, this mistake is common because Roth IRAs involve contribution limits, income thresholds and withdrawal rules that are often misunderstood.
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Treating a Roth IRA Like a Savings Account
Another common mistake Bergman sees is middle-class taxpayers treating a Roth IRA as a savings account rather than an investment account.
“A Roth IRA is not just a savings account; it is an investment account. Choosing the right investments can significantly boost your long-term gains,” Bergman said. “Since Roth IRA withdrawals are tax-free, it is a great place to hold investments with high growth potential. Failing to invest appropriately can significantly reduce the long-term benefit of tax-free compounding.”
Errors on Tax Returns
Some of the most common errors that the IRS reports with respect to individual tax returns are math errors, missing or incorrect Social sSecurity numbers and missing signatures on tax forms, according to Michele Frank, associate professor of accountancy and CPA at Miami University.
“These errors are annoying because they can often delay the processing of your return, which means it will take much longer to receive any refund that you are due,” Frank explained. “The use of tax preparation software may prevent taxpayers from making these types of errors.”
Another common error relates to the child tax credit. To be eligible, a child must be under the age of 17 at the end of the tax year, but some taxpayers, according to Frank, accidentally claim for children who are 17.
“Again, the use of tax prep software might help prevent this issue,” she explained. “In addition, only one parent can claim the credit. So if divorced parents fail to communicate and both claim the credit for the same child, their returns are likely to be flagged.”
Treating Extra Income Too Casually
When Poonja reviews tax returns for middle-class business owners and entrepreneurs, he often sees them treating a side business or consulting income casually, such as depositing checks without setting aside taxes and missing quarterly estimated payment deadlines, then facing tax bills and penalties in April.
“Many in the workforce underwithhold for outside consulting income: assuming they’ll be taxed at an ordinary rate. But they will likely have tax liability for their minimum 10% contribution, based on the higher of these three factors and in fact, it could even reach 32% to 35%,” Poonja added.
According to Poonja, this problem is also compounded when employees who qualify for home office deductions do not take them or make expense calculations that may invite an audit. “The IRS insists that the space must be used exclusively and regularly for business; a rule often misunderstood,” he said.
Early Withdrawals
Early withdrawals are another costly and common error. While there’s nothing stopping you from withdrawing contributions at any age, Bergman noted that doing so before age 59 1/2 may trigger penalties or taxes. There’s a 10% early withdrawal penalty plus income taxes, unless you qualify for an exception.
“Withdrawing earnings early can have a significant long-term impact, as it not only reduces current savings but also eliminates decades of potential compound growth,” Bergman said.
Not Itemizing
According to Frank, many middle-class taxpayers often assume that if they haven’t itemized in the past, usually because their itemizable deductions are less than the standard deduction, it won’t be worth the time to see if they should itemize this year.
“Given pretty significant tax law changes this past year, taxpayers may want to double-check this assumption,” she explained. “For example, in prior years, single taxpayers and married taxpayers filing a joint tax return were only allowed an itemized deduction for up to $10,000 of amounts paid for state and local taxes. However, in 2025, this cap was increased to $40,000.”
Frank explained that this increase means that more taxpayers, particularly those living in high-tax states, might benefit from itemizing rather than taking the standard deduction.
Caitlyn Moorhead contributed to the reporting for this article.
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This article originally appeared on GOBankingRates.com: Tax Planners: The Costliest Mistakes the Middle-Class Makes on Taxes
