Why these deductions matter

Running a business from home creates a mix of personal and business expenses. Properly identifying and documenting the business portion can reduce taxable income, lower self-employment tax exposure and improve cash flow. In my practice advising small-business owners for over 15 years, I regularly find missed deductions that collectively total thousands of dollars per taxpayer when reviewed and claimed correctly.

Key deductions home-based businesses often overlook

Below are the commonly missed deductions, how they work in practice, and what to record.

1) Home office deduction (simplified and regular methods)

  • What it is: A deduction for the portion of your home used regularly and exclusively for business. You can choose the simplified method ($5 per square foot up to 300 sq. ft., max $1,500) or the regular method (actual expenses prorated by business-use percentage).
  • How to calculate (examples): Simplified — a 200 sq. ft. office × $5 = $1,000. Regular — if your home is 1,000 sq. ft. and office is 200 sq. ft., the business-use percentage is 20%; multiply that percentage against eligible home expenses (utilities, insurance, repairs, and the business portion of mortgage interest or rent) per IRS Publication 587 (see: https://www.irs.gov/businesses/small-businesses-self-employed/home-office-deduction).
  • Reporting: Sole proprietors normally report home office deductions on Schedule C; the regular method uses Form 8829 to compute and carry the deduction. (IRS Pub. 587)
  • Common pitfall: The space must be used exclusively and regularly for business. Occasional or mixed personal use typically disqualifies the deduction for that portion.

2) Utilities, internet and phone

  • What qualifies: A portion of electricity, water, home internet and the business portion of phone service. If lines are shared for personal use, prorate the expense based on a reasonable method (square footage, hours used, or number of users).
  • Documentation: Monthly bills, a usage log or screenshots from an accounting app. Keep separate business-only accounts where possible.
  • Reference: For deeper guidance, see our article on how to track work-from-home expenses: How to Track Work-From-Home Expenses for Tax Time.

3) Equipment, supplies and small business property

  • What it includes: Computers, printers, office furniture, software subscriptions and eligible office supplies. For larger purchases, Section 179 expensing or bonus depreciation may allow you to deduct more in year one; smaller items can be deducted immediately as supplies.
  • Tax rules: Depreciation and expensing rules change, so check the latest IRS guidance (Pub. 946) and consult your tax professional before applying Section 179.

4) Vehicle and mileage expenses

  • How it works: If you use a vehicle for business tasks (meetings, client sites, deliveries), you can deduct either actual vehicle expenses or the standard mileage rate for business miles. Keep a contemporaneous mileage log showing date, purpose, start/stop odometer readings and miles driven.
  • Rate and documentation: For a summary of record and rate guidance see IRS Topic No. 505 (Business Use of Car) (https://www.irs.gov/taxtopics/tc505).

5) Business insurance, subscriptions and professional fees

  • Deductible items include business liability insurance, professional subscriptions (trade journals, online services), continuing education directly related to your trade, and legal/accounting fees tied to the business. Keep invoices and a clear explanation of business purpose.

6) Startup and organizational costs

  • Early-stage businesses can amortize or deduct a portion of startup costs in year one subject to limits. If you recently began operations, track pre-opening expenses and consult Pub. 535 for specifics.

7) Depreciation of part of the home used for business

  • If you use the regular method, you’ll likely allocate a portion of the home’s basis to depreciate the business-use part of the property. Depreciation has tax and sale implications (adjusted basis), so maintain records of cost basis, improvements and depreciation taken.

Who can claim these deductions?

  • Self-employed individuals, sole proprietors and partners who run a trade or business from home (reported on Schedule C or a trade/profession partnership return) are typically eligible.
  • Employees: Unreimbursed employee business expenses for work-from-home are currently suspended for most wage-earners through tax year 2025 under the Tax Cuts and Jobs Act; employees should rely on employer reimbursement under an accountable plan or consult a payroll/tax advisor.
  • S corporations and partnerships: These entities typically reimburse or account for home-related expenses differently (accountable plans or fringe benefit reporting). Speak to a tax professional to structure reimbursements correctly.

Practical recordkeeping and audit preparedness

  • Set up clear categories in your accounting system: home office, utilities, internet, telephone, equipment, vehicle, insurance, and professional fees.
  • Keep contemporaneous logs: for mileage, client appointments and hours the office is used. Mobile apps or accounting platforms that export reports are a huge time-saver.
  • Save receipts and back them up digitally with date stamps.
  • If audited, the IRS will look for exclusive use, business purpose and reasonable allocation methods — see our guide on audit preparedness: Preparing for an IRS Office Audit: Checklist.

Common mistakes and how to avoid them

  • Mistake: Claiming an office that isn’t used exclusively for business. Fix: Reassign space or use a dedicated area that meets the exclusive-and-regular-use rule.
  • Mistake: Treating all internet/phone bills as 100% business. Fix: Keep a usage log or separate business lines/subscriptions.
  • Mistake: Failing to track mileage contemporaneously. Fix: use a mileage app or maintain a dated paper log with trip purpose.
  • Mistake: Misapplying employee rules. Fix: confirm your status (employee vs. independent contractor) and follow the rules for that classification.

What to do if you missed deductions in a prior year

  • You can generally file an amended return (Form 1040-X) within the statute of limitations (usually three years from the original filing date or two years from tax payment, whichever is later) to claim missed deductions. For step-by-step guidance see our article: Filing an Amended Return for Missed Business Deductions.

Audit triggers and risk management

  • Red flags include unusually large home office deductions relative to income, claiming nonexclusive spaces, or claiming 100% of shared utilities. Keep documentation showing how you calculated business-use percentages and why your methods are reasonable.

Quick checklist before filing

  • Confirm eligibility (regular and exclusive use; principal place of business).
  • Choose method (simplified vs. regular) and calculate both to see which gives a better outcome.
  • Record mileage daily or use an app; retain receipts for vehicle expenses if using actual-cost method.
  • Keep receipts and explanation for equipment purchases; track depreciation and Section 179 elections.
  • Save copies of Form 8829 (if used) and related worksheets for at least three years.

Helpful authoritative resources

Professional disclaimer
This article is educational and not individualized tax advice. Rules change and individual circumstances vary. Consult a qualified tax professional or CPA for personalized advice and for confirmation of limits such as Section 179 thresholds and depreciation conventions applicable in the year you file.

Final note from the author
In my practice I’ve found that routinely reviewing home office classification, keeping contemporaneous logs and comparing the simplified vs. regular method annually yields the best tax outcomes. Small changes in recordkeeping often unlock deductions that were previously missed.

(Internal links: Home Office Deduction, How to Track Work-From-Home Expenses for Tax Time, Preparing for an IRS Office Audit: Checklist).