Sole proprietor and S corporation taxes in Massachusetts
Many owner-led businesses start on Schedule C, and some later elect to be taxed as an S corporation. These guides explain how each stage is taxed, federally and in Massachusetts, and what an honest comparison between the two has to include.
A sole proprietor, or a single-member LLC that has made no election, reports business profit on Schedule C of the federal return and on Schedule C of Massachusetts Form 1. Profit is subject to income tax and to self-employment tax, which for 2026 is 15.3% on net earnings up to the $184,500 Social Security wage base and 2.9% above it. That self-employment tax is the number an S corporation election changes: the owner is paid a reasonable salary through payroll, and profit above that salary can come out as distributions that carry no Social Security or Medicare tax.
The federal saving is the part national calculators show. The Massachusetts costs are the part they leave out. Every S corporation owes at least the $456 minimum corporate excise and files Form 355S alongside the federal Form 1120-S. An owner on W-2 becomes part of the business's covered workforce for Paid Family and Medical Leave (0.88% in 2026, or 0.46% for employers with fewer than 25 covered individuals; the 2027 rate has not been set yet), and unemployment insurance may apply to the owner's wages as well. Add a payroll provider, a second return and tighter bookkeeping, and the break-even point moves.
Some costs run the other way. Only an S corporation or partnership can elect the Massachusetts pass-through entity excise under Chapter 63D, and from tax year 2026 a new Chapter 63E excise applies to income above the 4% surtax threshold. Both can matter for owners who itemize or who have a large year, and neither is available to a disregarded single-member LLC. The guides below are grouped by where you are: learning the rules, weighing the options, or getting the work done.
Understand the rules
How the rules work, federally and in Massachusetts, in plain language.
What is self-employment tax? 2025 and 2026 rates explained
Self-employment tax is 15.3% of 92.35% of your net profit, with Social Security capped at $176,100 for 2025 and $184,500 for 2026. How it works in Massachusetts.
Read →How is a single-member LLC taxed in Massachusetts?
A single-member LLC is disregarded by default, so profit goes on your Schedule C federally and in Massachusetts. What the LLC changes, and the elections.
Read →What is an S corporation? A plain-English guide for Massachusetts owners
An S corporation is a tax status, not a type of company. Who can elect it, how owners are paid, and what Massachusetts adds: Form 355S and a $456 minimum excise.
Read →Schedule C basics for Massachusetts sole proprietors
How a sole proprietor's profit moves from Schedule C to Schedule SE, Form 1040 and the Massachusetts Schedule C on Form 1, and the records each line depends on.
Read →The QBI deduction after the 2025 tax law: what small business owners need to know
The QBI deduction no longer ends after 2025. The 2026 thresholds, the wider phase-in, the new $400 minimum, and why S corporation salary is not QBI.
Read →1099-NEC and 1099-MISC: the $2,000 threshold starting with 2026 payments
Forms 1099-NEC and 1099-MISC now start at $2,000 for payments made after 31 Dec 2025. What stays at $600 or $10, and the 1 Feb 2027 due date for 2026 forms.
Read →Form 1099-K for small businesses: the $20,000 and 200-transaction rule
Apps and marketplaces send Form 1099-K only above $20,000 and 200 transactions. All business income is still reportable. How to reconcile the form to your books.
Read →Business deduction documentation basics
What the IRS expects a business expense record to show, which expenses need extra proof, how long to keep records, and the monthly habits that make it routine.
Read →Massachusetts small business tax calendar, 2026 to 2027
Federal and Massachusetts due dates for sole proprietors and S corporations from October 2026 to April 2027: estimates, 1099s, 1120-S, 355S, 2553 and payroll.
Read →Section 179 and bonus depreciation: why your Massachusetts deduction differs
Federal law allows 100% bonus depreciation and a $2.5M Section 179 limit. Massachusetts disallows bonus and uses the older 179 limits for 2025 and 2026.
Read →How LLCs and corporations are taxed in Massachusetts
The legal entity and the tax classification are separate choices. How sole props, LLCs, S corps and C corps are taxed federally and in Massachusetts, side by side.
Read →
Weigh your options
Comparisons, checklists and the questions that decide which way to go.
LLC vs S corp: what actually changes, and what to ask before you elect
An LLC can be an S corp. What an S election changes for a Massachusetts owner: tax, payroll, returns and state costs, plus the questions to settle first.
Read →When does an S corporation make sense? A Massachusetts break-even guide
There is no profit level at which an S corp always pays. The moving parts, Massachusetts costs and illustrative 2026 scenarios that show where the line falls.
Read →S corp savings: what the math must include
The inputs and outputs an honest S-corp savings comparison needs in Massachusetts, what quick estimates leave out, and why the result is an estimate.
Read →Reasonable compensation for S corporation owners: how salary is set and documented
How the IRS approaches an S-corp owner's salary: the FS-2008-25 factors, the source-of-receipts test, the court cases, and how to document your figure.
Read →What an S corporation really costs in Massachusetts
Every recurring cost an S election adds in Massachusetts: the $456 minimum excise, PFML, UI, federal unemployment tax, payroll, extra returns and bookkeeping.
Read →Sole proprietor vs S corporation in Massachusetts: a side-by-side comparison
The same Massachusetts business run two ways: returns, employment tax, QBI, excise, PFML and payroll side by side, with an illustrative 2026 example.
Read →S corporation questions business owners ask, with straight answers
Election timing, one-owner S corps, spouses, losses, basis, health insurance, retirement and revoking: plain answers for Massachusetts owners, with sources.
Read →What changes after an S corporation election
After the S election: owner payroll, a W-2, new estimates, Form 1120-S and MA 355S, K-1s, an accountable plan and PFML registration. A Massachusetts checklist.
Read →S corporation readiness worksheet
A discussion worksheet for owners weighing an S corporation election: profit, pay, payroll, records, Massachusetts costs and timing. Questions, not a score.
Read →Salary vs distributions in an S corporation: timing, basis and records
How S corporation owners should take money out: wages before distributions, why owner draws cause trouble, what basis is and how the books should record each.
Read →Health insurance and retirement contributions for S corporation owners
How S corporation owners with over 2% get health premiums onto the W-2 and deducted, and why retirement contributions follow the salary, not the K-1 profit.
Read →Massachusetts PTE excise: 63D, the new 63E, and whether electing is worth it
How the Massachusetts 63D and new 63E pass-through entity excises work for S corporations from 2026: who can elect, estimates, and what decides it.
Read →The Massachusetts 4% surtax and your business income
How the Massachusetts 4% surtax reaches business owners: 2025 and 2026 thresholds, joint returns, one-time sale years and the new 63E excise.
Read →Missed the S corp deadline? How late election relief works
What happens when Form 2553 is late, how Rev. Proc. 2013-30 relief works within 3 years and 75 days, what shareholders sign, and how Massachusetts follows.
Read →Payroll setup checklist for new S corporation owners: who does what
The registrations, filings and decisions a new Massachusetts S corporation needs before the first owner paycheck, and a simple way to agree who handles each one.
Read →S corporation bookkeeping checklist: monthly, quarterly and year-end
What S corporation books need beyond a Schedule C ledger: officer wages, distributions, shareholder loans, accountable plans, basis and year-end steps.
Read →
Get it done
Deadlines, what to gather, and how working with us actually runs.
S corporation tax return preparation (Form 1120-S and Massachusetts Form 355S)
What goes into an S corporation's federal and Massachusetts returns, the 2026 and 2027 due dates, late penalties, and what to send us to start.
Read →Bookkeeping for S corporations
What S corporation books need that a sole proprietor's do not: owner wages, distributions kept apart from loans, monthly reconciliations, a clean year end.
Read →Accounting support for S corporation owners
Help at each stage of owning an S corporation in Massachusetts: deciding whether to elect, the first year after, the monthly books and the annual returns.
Read →Small business accountant in Easton, MA
Murphy Accounting is at 187 Washington Street in North Easton. Bookkeeping, business tax preparation and planning, and payroll support for owner-led businesses.
Read →
Quick answers
- Is a single-member LLC taxed differently from a sole proprietorship in Massachusetts?
- Not by default. Massachusetts classifies an LLC the same way it is classified federally, so a single-member LLC with no election is disregarded and its profit goes on the owner's Schedule C, exactly as a sole proprietor's would. The LLC is a legal structure registered with the Secretary of the Commonwealth, which files its own annual report, but it does not change the income tax unless the LLC elects corporate or S corporation treatment.
- At what profit does an S corporation start to make sense?
- There is no single number. The answer depends on what a reasonable salary for your role would be, your other household wages, the $456 Massachusetts minimum excise, PFML and possibly unemployment insurance on your wages, payroll and return preparation costs, and how the salary reduces your qualified business income deduction. Rules of thumb skip most of those items. We can run the comparison with your actual numbers.
- Does the IRS say how much salary an S corporation owner must take?
- No. The IRS says there are no specific guidelines for reasonable compensation in the Code or the Regulations. It points to the factors courts use, such as your training and experience, your duties, the time you put in, and what comparable businesses pay for similar services. Percentage splits you may see online, including the so-called 60/40 split, are not IRS rules. The salary should be one you can explain and document.
- When is the deadline to elect S corporation status for 2027?
- For a calendar-year business, Form 2553 must be filed no more than 2 months and 15 days after the start of the tax year the election is to take effect, which puts the 2027 deadline at 15 March 2027. It can also be filed at any time during 2026 for a 2027 start. If the deadline has passed, the IRS has a late-election relief procedure for owners with reasonable cause.
- What does an S corporation file in Massachusetts?
- An S corporation files Form 355S with Schedule S and an SK-1 for each shareholder, due on the 15th day of the third month after the tax year ends, the same timing as the federal Form 1120-S. Massachusetts requires electronic filing and grants an automatic six-month extension if the payment requirements are met. Every S corporation owes at least the $456 minimum excise.
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