7 Mistakes You Are Making with Tax Preparation (and How to Fix Them Before 2026)

Tax season is stressful enough without making costly mistakes that could delay your refund or trigger an audit. Every year, millions of taxpayers make preventable errors that cost them time, money, and peace of mind. The good news? Most of these mistakes are completely avoidable once you know what to watch for.

As we approach the 2026 tax season, now's the perfect time to learn from the most common tax preparation blunders and set yourself up for success. Whether you're filing your own return or working with a professional, understanding these pitfalls will help ensure your tax preparation goes smoothly.

1. Making Math Errors That Cost You Money

Simple arithmetic mistakes are surprisingly common: the IRS identified nearly 2.5 million math errors on returns filed in recent years. These aren't just basic addition and subtraction mistakes. They include selecting the wrong number from tax tables, miscalculating percentages for credits, and making errors in more complex calculations.

How to Fix It: Double-check every calculation, even if you're using tax software. Most programs handle the math automatically, but you still need to verify that your inputs are correct. Before submitting your return, take an extra 10 minutes to review all numbers. If you're calculating by hand, consider using a calculator twice or asking someone else to verify your work.

2. Choosing the Wrong Filing Status

Your filing status determines your standard deduction, tax rates, and eligibility for certain credits. Yet many taxpayers automatically choose "single" or "married filing jointly" without considering whether another status might save them money. The difference between filing statuses can mean hundreds or even thousands of dollars in tax savings.

How to Fix It: Don't assume you know your correct filing status. Use the IRS's Interactive Tax Assistant tool to determine which status applies to your situation. If multiple statuses seem applicable, calculate your taxes under each scenario to see which results in the lowest tax liability. Common overlooked statuses include "head of household" for single parents and "married filing separately" in certain situations.

3. Missing Valuable Deductions and Credits

This is perhaps the costliest mistake of all. The IRS won't automatically add deductions or credits you forgot to claim: they'll only fix math errors in your favor. Many taxpayers miss out on significant savings by not claiming the Child and Dependent Care Credit, education credits, home office deductions, or charitable contributions.

How to Fix It: Before filing, create a comprehensive list of all possible deductions and credits. Keep detailed records throughout the year of eligible expenses, including receipts for charitable donations, medical expenses, business costs, and educational expenses. Consider working with a tax professional who stays current on all available tax benefits, or use comprehensive tax software that prompts you about potential savings.

4. Getting Personal Information Wrong

Misspelled names and incorrect Social Security numbers cause significant processing delays every year. Each name on your return must match exactly what appears on the corresponding Social Security card. Even a single letter difference: like "Jon" instead of "John": can cause problems.

How to Fix It: Before filing, gather all Social Security cards for yourself, your spouse, and any dependents you're claiming. Compare each name and number on your tax return against the actual cards. If there are discrepancies between the name on someone's Social Security card and their current legal name, contact the Social Security Administration to update their records before filing your taxes.

5. Entering Wrong Banking Information

If you're expecting a refund via direct deposit, entering incorrect routing or account numbers will delay your money. In worst-case scenarios, your refund could be deposited into someone else's account, requiring you to work with both the bank and IRS to recover it.

How to Fix It: Verify your banking information by checking a recent bank statement or contacting your bank directly. Don't rely on memory or old checks: account numbers can change. If you're unsure about your numbers, choose to receive a paper check instead. It may take slightly longer, but it's safer than risking a misdirected deposit.

6. Making Paper Filing Mistakes

While most taxpayers file electronically, those who still file paper returns often make preventable errors. Common mistakes include forgetting to sign and date the return, not including sufficient postage, sending the return to the wrong IRS processing center, or arranging forms in the wrong order.

How to Fix It: If you must file by paper, create a detailed checklist before mailing. Ensure your return is signed and dated by both spouses if married filing jointly. Use certified mail with a return receipt to prove the IRS received your return. Better yet, consider switching to electronic filing, which eliminates most of these errors and processes much faster.

7. Filing at the Wrong Time

Filing too early without all necessary documents can result in amended returns, while filing late incurs expensive penalties. Many taxpayers rush to file in January before receiving all their tax documents, then must file costly amendments later.

How to Fix It: Wait until you've received all tax documents before filing. Most employers send W-2s by January 31, and financial institutions send 1099s by the same deadline. If you haven't received expected documents by mid-February, contact the issuer. If you can't file by the April deadline, request an extension using Form 4868, which gives you until October 15 to file. Remember, an extension to file isn't an extension to pay: estimate your tax liability and pay any amount due with your extension request.

Getting Professional Help When You Need It

Tax laws change frequently, and what worked last year might not be optimal this year. If your tax situation involves any complexity: like starting a business, buying a home, significant life changes, or substantial investments: consider working with a qualified tax professional.

Professional tax preparers stay current on tax law changes and can often identify deductions and credits you might miss. They can also represent you if the IRS has questions about your return, providing valuable peace of mind.

Start Preparing Now for 2026

Don't wait until tax season to think about your taxes. Start organizing your records now, keep receipts for deductible expenses, and consider any year-end tax planning strategies that might apply to your situation.

Good tax preparation is really about good record-keeping throughout the year. Set up a simple filing system for tax documents, keep digital copies of important receipts, and stay informed about tax law changes that might affect you.

By avoiding these seven common mistakes, you'll save time, reduce stress, and potentially save significant money on your 2026 tax return. Remember, the goal isn't just to file your taxes: it's to file them accurately and claim every benefit you're entitled to receive.

If you need help navigating any of these issues or want professional guidance for your tax preparation, don't hesitate to contact us at Smith Taxes & More. We're here to help ensure your tax filing experience is as smooth and beneficial as possible.