If you’ve been running a contracting business on the Cape for any length of time, you’ve probably had at least one year where the tax bill was a lot bigger than you expected.
Not because you did anything wrong. Just because nobody sat you down and explained how self-employment taxes actually work before you filed your first Schedule C.
It’s one of the most common conversations we have with new contractor clients. You think you made $80,000, you set aside maybe 20% for taxes the way you heard you’re supposed to, and then you owe more than you planned for.
The culprit is almost always the self-employment tax, which is separate from your income tax and applies before the income tax conversation even starts.
So let’s walk through how to avoid the self-employment tax trap, what you can do about it, and why getting your Cape Cod taxes handled by someone who knows contractor financials makes a real difference.
What is Self-Employment Tax and Why Does It Hit Contractors So Hard?
Self-employment tax (SE tax) is how the IRS collects Social Security and Medicare from people who work for themselves. When you’re an employee, your employer pays half of these taxes on your behalf and withholds the other half from your paycheck. When you’re a contractor, there’s no employer, so you pay both halves yourself.
For 2026, the self-employment tax rate is 15.3% on net self-employment income up to the Social Security wage base of $184,500, and then 2.9% on anything above that for Medicare.
So if you net $80,000 from contracting, you owe roughly $11,304 in SE tax, figured on Schedule SE, before your income tax calculation even begins. That comes out first, and most contractors don’t see it coming until April.
The good news is you can deduct half of your SE tax as an above-the-line deduction. So on that $11,304 bill, roughly $5,652 comes off your adjusted gross income before income tax is calculated.
It helps, but it doesn’t eliminate the bill, and when you pay it matters as much as what you owe.
Quarterly Estimated Taxes Are Required, Not Optional
Because nobody is withholding from your paychecks, the IRS expects you to pay throughout the year, not in one lump sum at filing. These are called estimated tax payments, and the deadlines for 2026 are April 15, June 15, September 15, and January 15, 2027.
Miss one and you’re looking at an underpayment penalty, even if you pay everything in full when you file in April. The IRS sets that interest rate quarterly, and it has sat at 7% for most of 2026. It’s not catastrophic, but it’s completely avoidable.
A rough rule of thumb for Cape Cod contractors: set aside 25 to 35% of every check you receive, nearer the low end under $100,000 in net income and nearer the top above it. That covers SE tax plus federal income tax for most people, because the income tax brackets stack on top of an already meaningful SE tax bill.
That’s what you owe. Which brings us to everything you’re allowed to subtract before the calculation even starts.
The Deductions Most Contractors on the Cape Miss
The self-employment tax applies to net income, not gross revenue. Every legitimate business deduction reduces the number the SE tax is calculated on, which means deductions save you more than most people realize once you count both SE tax and income tax.
Common deductions for Cape Cod contractors that often go unclaimed: home office (if you do your estimating and scheduling from a dedicated space at home), vehicle mileage for job site travel, tools and equipment, materials purchased for jobs, business insurance, subcontractor payments, and professional fees including accounting.
The IRS standard mileage rate is 72.5 cents per mile for business driving between January and June 2026, and 76 cents from July onward. That adds up fast if you’re running between job sites across the Cape all season.
The catch is that all of these require documentation. Keep a running mileage log from day one of the year, and photograph your receipts the day you get them. The contractors who do that save real money. The ones reconstructing everything in March save considerably less.
Deductions only go so far, though. Once your net profit climbs, the bigger lever is the structure of the business itself, and that decision changes how much SE tax you pay at all.
Does an S-Corp Election Actually Help Cape Cod Contractors?
For contractors earning over roughly $50,000 to $60,000 in net profit, an S-corporation election is worth a serious conversation. The reason: as an S-corp owner, you pay yourself a reasonable salary (which is subject to payroll taxes), and take the remaining profit as a distribution, which is not subject to SE tax. Done correctly, this meaningfully reduces your SE tax exposure.
The tradeoff is real administrative cost: payroll processing, quarterly payroll tax filings, a separate business return (Form 1120-S), and a salary the IRS won’t challenge. For most contractors under $50,000 net, that admin tends to outweigh the savings. Above it, model both scenarios before deciding.
This is exactly the kind of question we walk through at our Cape Cod accounting office, usually at a mid-year check-in rather than in January when there’s nothing left to do.
The next problem is that on the Cape, the money doesn’t arrive evenly across the year.
How Seasonal Income Complicates The Quarterly Payment Calculation
Cape Cod contractors often earn the bulk of their income between April and October, with a much slower off-season. That swing creates a real problem with estimated payments, because the IRS calculates underpayment penalties as if your income arrived evenly all year.
There’s a way around it: the annualized income installment method, which lets you base each quarterly payment on what you actually earned that quarter rather than an annual estimate. If most of your income lands between April and September, this keeps you from overpaying early while still covering you later. It requires filing IRS Form 2210 with your return.
Most contractors don’t know it exists, which is fair, because the IRS doesn’t advertise it. The question then becomes who’s actually working alongside you on those summer jobs.
Worker Classification Is The Other Trap Nobody Warns You About
Massachusetts uses one of the strictest worker classification tests in the country, the ABC test, and contractors who hire helpers need to pay attention to it. A worker is presumed to be an employee unless you can show all three: the person is free from your control and direction, the work is outside the usual course of your business, and they operate an independent trade of their own.
Get this wrong, and the consequence isn’t just a fine. You could owe back payroll taxes, unemployment insurance contributions, workers’ comp premiums, and penalties going back years. We’ve seen a contractor hire a helper for one summer season and face a state audit years later.
If you’re regularly using the same person as a 1099 subcontractor and they work primarily for you, on your projects, with your tools, that classification is worth reviewing before it becomes a problem. Which brings us to the last lever, and the one contractors most often misunderstand.
Retirement Contributions Cut Your Income Tax, Not Your SE Tax
A Solo 401(k) or SEP-IRA lets self-employed contractors put away a substantial chunk of income before taxes. One thing to be clear about, because it gets repeated wrong constantly: for a sole proprietor, these contributions reduce your income tax, not your self-employment tax. SE tax is calculated on your Schedule C profit before the retirement deduction comes off.
It’s still one of the largest deductions available to you. It just doesn’t touch the SE tax line.
For 2026, a SEP-IRA allows contributions up to $72,000. A Solo 401(k) reaches the same ceiling, with up to $24,500 of it coming from your own employee deferral.
For a contractor netting $100,000 in a good year, a maxed SEP-IRA contribution works out to roughly $18,600 off taxable income.
One caution on that math: the rate everyone quotes is 25%, but for a sole proprietor the real figure is 20% of net earnings after the half-SE-tax deduction. Getting it wrong is a common way contractors plan for a contribution they can’t actually make.
The other catch is that you have to open the account and fund it. It doesn’t happen automatically. Which brings you back to this year’s payments, if you’re already behind on them.
What To Do If You’re Already Behind On Estimated Taxes This Year
If you’ve skipped one or more quarterly payments, pay what you can as soon as possible. Underpayment penalties accrue based on how long the underpayment exists, so paying late still beats not paying. The September 15 deadline for Q3 2026 is coming up fast, and making that payment even if Q1 and Q2 were short limits how much the penalty compounds.
If you’re not sure how much you owe across all four quarters, or whether you qualify for a penalty exception, that’s the moment to sit down with a CPA rather than guessing.
The IRS safe harbor rule says you generally avoid underpayment penalties if you’ve paid 100% of last year’s tax liability, or 90% of the current year’s tax.
If your prior-year income was over $150,000, that first number becomes 110% instead. Working out which applies to you, and how to get there before year-end, is something we do regularly.
If any of this sounds familiar, we’re happy to walk through the numbers with you. You can reach us at our contact page to get started.
If you liked this one, you might also like our tax tips for the self-employed, or our guide to hiring your first employee on Cape Cod, which covers the same classification territory from the employer side.
Until next time!
About the Author
Steven M. Ellard, CPA is the founder of Steven M. Ellard, CPA, a Brewster, Massachusetts public accounting firm serving small businesses, restaurants, healthcare practices, homeowners associations, and individuals across Cape Cod, the South Coast, and Greater Plymouth. The firm provides monthly bookkeeping, payroll, individual and business tax preparation, QuickBooks cleanup, business foundation services, and outsourced CFO and advisory work. Meet the team or get in touch.