Common Tax Mistakes to Avoid
Learn about the most frequent tax filing errors and how to avoid them to maximize your refund and minimize IRS issues.
Filing your taxes can be complex, and even small mistakes can lead to delays in processing, reduced refunds, or IRS audits. Here are the most common tax mistakes people make and how to avoid them.
1. Math Errors and Calculation Mistakes
The Problem: Simple arithmetic errors are one of the most common mistakes on tax returns. Adding up income incorrectly, miscalculating deductions, or making errors in tax bracket calculations can all lead to problems.
✅ How to Avoid:
- Use tax software or professional tax preparers
- Use our calculators to verify your numbers before filing
- Double-check all math, especially when filing paper returns
- Let IRS e-file software catch calculation errors automatically
2. Incorrect or Missing Social Security Numbers
The Problem: Entering the wrong Social Security Number (SSN) for yourself, your spouse, or your dependents is a major red flag for the IRS and will delay processing.
✅ How to Avoid:
- Verify SSNs against Social Security cards before filing
- Ensure names match exactly what's on Social Security cards
- Update the Social Security Administration if names have changed (marriage, divorce, etc.)
- Never guess or estimate SSNs
3. Filing Status Errors
The Problem: Choosing the wrong filing status (Single, Married Filing Jointly, Head of Household, etc.) can significantly impact your tax bill and may trigger an audit.
✅ How to Avoid:
- Review IRS filing status rules carefully
- Head of Household has specific requirements—verify you qualify
- Consider both Married Filing Jointly and Separately to see which is better
- If divorced or separated, understand which parent claims dependents
4. Not Reporting All Income
The Problem: Failing to report income from side gigs, freelance work, investment earnings, unemployment benefits, or other sources is a serious issue. The IRS receives copies of your W-2s, 1099s, and other income documents.
✅ How to Avoid:
- Report ALL income, even if you didn't receive a 1099
- Keep track of freelance and cash income throughout the year
- Report cryptocurrency gains, gambling winnings, and tips
- Include unemployment benefits (they're taxable)
- Wait until mid-February to ensure you've received all tax forms
5. Claiming Ineligible Dependents
The Problem: Claiming someone as a dependent who doesn't meet IRS qualifications, or having multiple people claim the same dependent, will trigger IRS scrutiny.
✅ How to Avoid:
- Verify dependents meet relationship, residency, age, and support tests
- Coordinate with ex-spouses on who claims children
- Get IRS Form 8332 if the non-custodial parent is claiming the child
- Remember: only one person can claim a dependent per year
6. Standard Deduction vs. Itemizing Confusion
The Problem: Many taxpayers don't realize they should take the standard deduction instead of itemizing, or vice versa. Since 2018, the standard deduction has nearly doubled, making itemizing less beneficial for most people.
✅ How to Avoid:
- Calculate both ways and choose the higher deduction
- Standard deduction for 2024: $14,600 (single), $29,200 (married)
- Itemize only if mortgage interest, SALT, medical, and charity exceed standard deduction
- Keep detailed records of deductible expenses throughout the year
7. Missing Tax Credits
The Problem: Tax credits directly reduce your tax bill dollar-for-dollar, but many people miss out on valuable credits they qualify for.
✅ How to Avoid:
- Research all available credits: Child Tax Credit, EITC, education credits, energy credits
- Earned Income Tax Credit (EITC) is often overlooked by eligible low-income workers
- American Opportunity Credit and Lifetime Learning Credit for education expenses
- Child and Dependent Care Credit for childcare costs
- Use tax software that prompts you to check for credits
8. Forgetting About Self-Employment Taxes
The Problem: Freelancers, gig workers, and small business owners often forget they owe both income tax AND self-employment tax (15.3% for Social Security and Medicare).
✅ How to Avoid:
- Set aside 25-30% of self-employment income for taxes throughout the year
- Make quarterly estimated tax payments to avoid penalties
- Use our Self-Employment Tax Calculator to estimate your liability
- Remember: you can deduct half of self-employment tax on your return
9. Incorrect Bank Account Information
The Problem: Entering the wrong routing or account number for direct deposit means your refund will be delayed or sent to the wrong account.
✅ How to Avoid:
- Triple-check routing and account numbers against a check or bank statement
- Ensure the account is in your name (IRS won't deposit to third-party accounts)
- Choose a checking account, not savings (some banks reject refund deposits to savings)
- Don't close your bank account before your refund arrives
10. Missing the Filing Deadline
The Problem: Failing to file by the April 15 deadline (or October 15 extension deadline) results in penalties and interest charges that can add up quickly.
✅ How to Avoid:
- File for an automatic 6-month extension (Form 4868) if you need more time
- Remember: an extension to file is NOT an extension to pay—you still owe taxes by April 15
- Set reminders well before the deadline to avoid last-minute rush
- If you owe taxes and can't pay, file anyway to avoid failure-to-file penalties
11. Forgetting State Taxes
The Problem: Many people focus on federal taxes and forget that most states also require tax returns. Some people who moved during the year need to file in multiple states.
✅ How to Avoid:
- Check your state's filing requirements—most states require returns
- If you moved, you may need to file part-year returns in both states
- Use our State Tax Calculator to estimate state taxes
- Some states have reciprocity agreements—research your situation
12. Not Keeping Good Records
The Problem: Without proper documentation of income, deductions, and credits, you can't defend your return if the IRS questions it. You're also more likely to miss deductions.
✅ How to Avoid:
- Keep all tax documents for at least 3 years (7 years for serious issues)
- Save receipts for deductible expenses: medical, charity, business, etc.
- Maintain digital or physical copies of W-2s, 1099s, and all tax forms
- Use accounting software or spreadsheets to track income and expenses throughout the year
💡 Pro Tips for Error-Free Filing
- 1.Use e-file: Electronic filing catches many errors automatically and processes faster than paper returns.
- 2.Review before submitting: Take a break, then review your entire return with fresh eyes before filing.
- 3.Use our calculators: Pre-calculate your taxes with our tools to verify your return is accurate before filing.
- 4.Consider professional help: If your situation is complex (rental property, business, investments), hire a CPA or EA.
- 5.File on time: Even if you can't pay, file your return to avoid steep late-filing penalties.
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Disclaimer: This guide provides general information about common tax mistakes and is not tax advice. Tax laws are complex and change frequently. For personalized advice regarding your specific situation, consult a qualified tax professional (CPA, EA, or tax attorney). TaxWiser provides calculators and educational resources but does not provide tax, legal, or financial advice.