What Expenses Can’t Be Written Off by Your Business?

Jun 2, 2024 | Business, Newsletter, Tax

If you check the Internal Revenue Code, you may be surprised to find that most business deductions aren’t specifically listed there. For example, the tax law doesn’t explicitly state that you can deduct office supplies and certain other expenses. Some expenses are detailed in the tax code, but the general rule is contained in the first sentence of Section 162, which states you can write off “all the ordinary and necessary expenses paid or incurred during the taxable year in carrying on any trade or business.”

Basic Definitions

In general, an expense is ordinary if it’s considered common or customary in the particular trade or business. For example, insurance premiums to protect a store would be an ordinary business expense in the retail industry.

necessary expense is one that’s helpful or appropriate. For example, a car dealership may purchase an automatic defibrillator. It may not be necessary for the business operation, but it might be helpful if an employee or customer suffers a heart attack. It’s possible for an ordinary expense to be unnecessary. But to be deductible, an expense must be ordinary and necessary.

A deductible amount must be reasonable in relation to the benefit expected. For example, if you’re attempting to land a $3,000 deal, a $65 lunch with the potential client should be OK with the IRS. (The Tax Cuts and Jobs Act eliminated most deductions for entertainment expenses but retained a 50% deduction for business meals.)

How the Courts May View Expenses

The deductibility of some expenses is clear, while others are more complicated. Not surprisingly, the IRS and courts don’t always agree with taxpayers about what is ordinary and necessary. To illustrate, here are three recent U.S. Tax Court cases in which specific taxpayer deductions were disallowed:

  1. A married couple owned an engineering firm. For two tax years, they claimed depreciation of $76,264 on three vehicles, but didn’t provide required details, including each vehicle’s ownership, cost and useful life. They claimed $34,197 in mileage deductions and provided receipts and mileage logs, but the court found they didn’t show related business purposes. The court also found the mileage claimed included commuting costs, which can’t be written off. The court disallowed these deductions and assessed taxes and penalties. (TC Memo 2023-39)
  2. The court ruled that a married couple wasn’t entitled to business tax deductions because the husband’s consulting company failed to show that it was engaged in a trade or business. In fact, invoices produced by the consulting company predated its incorporation. And the court ruled that even if the expenses were legitimate, they weren’t properly substantiated. (TC Memo 2023-80)
  3. A physician specializing in gene therapy deducted legal expenses of $360,295 for two years on Schedule C of his joint tax returns. The court found that most of the legal fees were to defend the husband against personal conduct issues. The court denied the deduction for personal legal expenses but allowed a deduction for $13,000 for business-related legal expenses. (TC Memo 2023-42)

These cases and others should show the importance of maintaining careful, detailed records. Make sure that only business costs are claimed.

Proceed with Caution!

If an expense seems like it’s not normal in your industry or could be considered personal or extravagant, proceed with caution. Contact the office with questions about deductibility and proper documentation.

One Big Beautiful Bill Act / Evolution of AI

One Big Beautiful Bill Act / Evolution of AI

BDO Digital Presentation BDO Digital’s discussion on how emerging technologies are rapidly changing financial processes, decision making, and operations at businesses across the country.Download the Presentation OBBBA Presentation The One Big Beautiful Bill Act of...

What to Know If You Receive an IRS Notice

What to Know If You Receive an IRS Notice

Notices from the IRS are more common than you may realize. Each year, the IRS mails millions of letters to clarify information, confirm changes or request additional documentation. Receiving a notice may seem intimidating, but most notices can be addressed quickly...

The IRS Criteria for Distinguishing Hobbies From Businesses

The IRS Criteria for Distinguishing Hobbies From Businesses

Turning a favorite pastime into income can be rewarding, but it raises an important tax question: Is the activity a hobby or a business? The answer matters because different tax rules apply to each. All income must be reported on your tax return, regardless of whether...

Common Growth Mistakes Small Businesses Make

Common Growth Mistakes Small Businesses Make

A recent survey found that 45% of small businesses reported growth, but 78% wanted to grow. This January 2026 data from Intuit QuickBooks Small Business Insights suggests that many small businesses are struggling to achieve their expansion goals. Small businesses...

Are College Scholarships Really Tax-Free?

Are College Scholarships Really Tax-Free?

Generally, scholarships received by degree candidates are tax-free to the extent they’re used for qualified tuition and related expenses. These include tuition, mandatory fees and required books, supplies and equipment. Amounts used for nonqualified expenses — such as...