S-Corp Tax Deductions & Write-Offs: What You Can (and Can't) Deduct

Part of WageProof's complete guide to S-corp reasonable compensation.

Most "S-corp write-off" lists are the same generic business-expense lists you'd find for any company. What actually matters for an S-corporation is the handful of deductions that work differently because you're both an owner and an employee — starting with your own salary. Here's what you can deduct, the S-corp-specific rules that trip people up, and what isn't deductible no matter who tells you otherwise.

How S-corp deductions work

An S-corporation deducts ordinary and necessary business expenses under 26 U.S.C. §162 — the same standard every business uses. Those deductions reduce the company's net profit, and because an S-corp is a pass-through entity, that lower profit is what flows through to your personal return. So a legitimate deduction saves you tax at your personal rate; it doesn't create a separate corporate refund.

The everyday categories are the same ones any business claims — worth a quick checklist so nothing gets missed:

• Payroll — wages to you and any employees, plus the employer share of payroll taxes.
• Rent and utilities for business space (or an accountable-plan reimbursement for a home office — more below).
• Software, subscriptions, and tools used in the business.
• Contractor and professional fees — subcontractors, your CPA, legal, bookkeeping.
• Advertising and marketing, including your website and ad spend.
• Business insurance (general liability, errors-and-omissions, etc.).
• Office supplies and equipment (equipment can be expensed under Section 179 or depreciated).
• Business travel and the business-use portion of vehicle costs.
• Business meals (generally 50% deductible) with a genuine business purpose.
• Continuing education and professional dues that maintain or improve your current business skills.
• Retirement plan contributions and employee benefits.
• Bank and merchant-processing fees, and interest on business loans.

None of those are S-corp-specific — they'd apply to a sole proprietorship too. The deductions worth understanding in detail are the ones tied to you as an owner-employee, because the rules genuinely differ.

Your salary is a deduction — which is the whole point

The wages your S-corp pays you are a deductible business expense, and so is the employer half of the payroll tax on them. That's not a footnote; it's the center of how the S-corp structure works.

Your reasonable compensation reduces the company's profit (good — it's deductible), but it's also subject to FICA (the cost of the S-corp deal). The profit left after your salary is taken as distributions, which avoid FICA. That's why the salary number is the one that matters: set it on defensible market data, and both halves of the equation — the deduction and the payroll tax — sit on solid ground. We cover the trade-off in How to Pay Yourself: Salary vs. Distribution.

A quick illustration: if your S-corp earns $150,000 before your pay and you take a defensible $90,000 salary, that salary is fully deductible to the company, and the remaining $60,000 of distributions avoids the 15.3% FICA that wages carry — worth roughly $7,400 a year. Push the salary below market to chase a bigger number and you've traded a few thousand dollars for audit exposure (there's no 60/40 shortcut). Run your own figures in the S-Corp Tax Savings Calculator.

The S-corp-specific deductions that work differently

These are the ones where being an S-corp owner-employee changes the rules.

Health insurance (the >2% shareholder rule). This is the most S-corp-specific deduction on the list and the one most often botched. If you own more than 2% of the S-corp, premiums the company pays for your health insurance follow a specific sequence:

1. The S-corp pays or reimburses the premium for your coverage.
2. The premium is added to your W-2 wages (Box 1) — so it's subject to income tax, but it's left out of the Social Security and Medicare boxes, so no FICA applies (when the coverage is provided under the corporation's health plan, as it normally is).
3. You then take the self-employed health insurance deduction on your personal return (Schedule 1), which offsets the income added in step 2.

Done right, the premium is effectively deductible without ever touching FICA. Done wrong — most often by paying the premium but never putting it on the W-2 — the IRS can disallow the personal deduction, which is why it's a frequent audit flag and a common point of friction with the IRS. The mechanics are laid out in the IRS guidance on S-corp compensation and medical insurance.

Home office and out-of-pocket costs — use an accountable plan. Because you're an employee of your own corporation, you generally cannot deduct a home office, mileage, or other out-of-pocket business costs on your personal return — the deduction for unreimbursed employee expenses was eliminated starting in 2018, which makes an accountable plan the only clean route, not just the best one. Under an accountable plan the company reimburses you and deducts the reimbursement, and the money isn't taxable income to you — as long as three conditions are met:

1. Business connection — the expense is a legitimate business expense.
2. Substantiation — you document it (receipts, a mileage log) within a reasonable time.
3. Return of excess — you repay any advance beyond your actual expenses.

It's a well-established mechanism and fully defensible when handled this way.

Retirement contributions. Contributions to a solo 401(k) or SEP-IRA are calculated from your W-2 wages — so an artificially low salary doesn't just invite an audit, it also caps how much you can put away tax-deferred. Another reason the salary should reflect real market value.

Equipment and vehicles. Capital purchases can be expensed under Section 179 or depreciated, subject to the annual limits. Business-use percentage matters — especially for vehicles, where the rules are stricter and personal use has to be backed out.

What you can't deduct

• Distributions. A distribution is a draw of profit that's already been taxed to you on your K-1 — it is not a business expense, so it's never a deduction. Treating distributions as if they reduce taxable income is simply wrong.
• Personal expenses. Commuting, personal meals, clothing, and the family-vacation-with-a-business-lunch don't become deductible because an S-corp paid for them. The "ordinary and necessary" test is real.
• An unreasonably high salary, in the other direction. Owners usually pay themselves too little, but overstating salary to manufacture deductions has its own problems — wages must also be reasonable for the work, judged on the same factors the IRS weighs. The defensible number cuts both ways.

Deductions and the QBI deduction

One deduction interacts with your salary in a way worth flagging: the Section 199A qualified business income (QBI) deduction. Your W-2 wages are generally not themselves QBI, so paying yourself more salary can shrink the QBI deduction — but wages also factor into the §199A limits at higher incomes, so the effect isn't one-directional. It's facts-and-income-dependent; we work through it in How the QBI Deduction Affects Your S-Corp Salary. As always, chasing a deduction is never a reason to set an indefensible salary.

How WageProof helps

Deductions are mostly your accountant's domain — but the single biggest S-corp number, your salary, is both your largest deduction and your largest audit exposure. WageProof builds that number from BLS wage data for your role and metro area and documents it, so the deduction is defensible and the distributions above it are clean. See the methodology, view a sample report, or start your report in about 15 minutes.

This article is general information, not legal or tax advice. S-corp deduction rules — especially the health-insurance and accountable-plan mechanics — depend on your specific facts; consult a qualified tax professional.