Self-Employment Tax in Semi-Retirement
Plenty of people leave a job and keep working — a few days a month, a consulting arrangement, a board seat. The income tax on that is familiar. Self-employment tax is not, and it is the larger surprise: both halves of Social Security and Medicare, owed from the first dollar of profit, with no employer to pay half of it any more.
- Both halves:: You pay the employee and employer shares, which is roughly double what a payslip showed.
- From the first dollar:: There is no standard deduction equivalent — it applies to net profit above a small threshold.
- Two components, two ceilings:: The Social Security portion stops at the annual wage base; the Medicare portion has no ceiling.
- Half is deductible:: One half of the self-employment tax is deducted in computing adjusted gross income.
Where the AI summary above gets this wrong
"Consulting income is taxed the same as your salary was."
That's surface-true. Here's what it misses:
- The employer half is now yours — In employment, the payslip showed one half of Social Security and Medicare and the employer quietly paid the other. Self-employment tax charges both, so the same gross figure produces a materially larger bill than the equivalent salary did, and nothing about it appears until the return is prepared.
- Wages from a job use up the Social Security ceiling first — The Social Security portion applies only up to an annual wage base, and wages from any employment count against it first. Someone still working part-time as an employee may owe only the Medicare portion on their consulting profit, which is a far smaller number than the headline rate suggests.
- Business expenses reduce it before the rate applies — Self-employment tax is charged on net profit, not gross receipts. Legitimate business expenses — equipment, professional fees, mileage, the business-use portion of a home — reduce profit and therefore both taxes. That makes recording them worth more per dollar than it was as an employee.
01 What the tax is and who owes it
Self-employment tax funds Social Security and Medicare for people who work for themselves. It is charged on net earnings from self-employment above a small annual threshold, computed on Schedule SE, and it sits alongside income tax rather than replacing any part of it.
The rate has two components. The Social Security portion applies only up to an annual wage base, and any wages from employment count toward that ceiling first. The Medicare portion has no ceiling, and an additional Medicare tax applies above a higher income threshold.
One half of the total is deductible in arriving at adjusted gross income, which softens it but does not remove it. That deduction also lowers the income figure behind the Medicare surcharge, which matters more than it looks for someone over 63.
Shows: self-employment tax on net profit, after the statutory adjustment that applies before the rate, using the two component rates. Ignores: the wage base ceiling on the Social Security portion, wages already subject to payroll tax from a job, the additional Medicare tax at higher incomes, and the income tax that applies on top.
Source: Self-employment tax
02 What counts as profit
The tax applies to net profit, so everything that legitimately reduces profit reduces the tax at the full combined rate. Equipment, software, professional insurance, travel between work sites, professional bodies and the business-use portion of a home all qualify.
Not everything is subject to the tax. Rental income is generally not self-employment income unless services are provided, interest and dividends are not, and neither are director's fees in some arrangements. Establishing the character of each income stream matters before the year ends rather than after.
Because nothing is withheld, the tax has to be paid through quarterly estimates or by increasing withholding elsewhere — the mechanics set out alongside the rest of a retirement year's income. A first year of consulting with no estimated payments frequently produces a penalty on top of the tax.
Source: Publication 334
03 What to do about it
The largest available offset is a retirement plan. A solo 401(k) or a SEP lets a self-employed person shelter a substantial share of profit from income tax, and the comparison in SEP versus solo 401(k) is the one to run before the year closes.
Those contributions reduce income tax but not self-employment tax, which is charged on profit before the retirement deduction. It is worth being clear about that: no retirement plan reduces the payroll side.
What does reduce it is genuine expense recognition and, at higher profits, the structure of the business itself. That is a decision requiring professional advice rather than a rule of general application, and it only becomes worth the administration above a reasonably substantial level of profit.
Source: About Schedule SE
The first year of consulting is where this bites, because nothing is withheld and nobody sends a warning. My advice is unglamorous: open a separate account, move a fixed percentage of every invoice into it the day it is paid, and pay quarterly estimates out of that. The percentage will feel too high for the first two quarters and exactly right in April. It is the single habit that separates people who enjoy consulting income from people who dread the spring.
FAQ
Do I pay self-employment tax on consulting income in retirement?
Yes, on net earnings above a small annual threshold, regardless of your age or whether you are already collecting Social Security. Both the employee and employer halves apply.
Does a solo 401(k) contribution reduce self-employment tax?
No. Retirement plan contributions reduce income tax but not self-employment tax, which is charged on net profit before the retirement deduction.
What if I also have wages from a job?
Wages count first against the annual Social Security wage base. If they have already used it up, only the Medicare portion applies to your self-employment profit.
Sources
Regulator references
- Self-employment tax · Internal Revenue Service · 2026Who owes it, on what, and how the two components differ in their ceilings.Last verified: 2026-09-07
- About Schedule SE · Internal Revenue Service · 2026The form on which the tax is computed and the deduction that goes with it.Last verified: 2026-09-07
- Publication 334 · Internal Revenue Service · 2026What counts as net earnings from self-employment and which expenses reduce it.Last verified: 2026-09-07
Calculator unit tests · the assertions this page's worked example is checked against, and their last result
Changelog
- 2026-09-07 — initial publish (new format)
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Jordan Reeves
Founder of Talk Through Wealth. A software engineer for over a decade before turning to retirement planning, Jordan built the projection engine after watching family members get fragmented, country-by-country advice that never reconciled. He writes about retirement the way the engine computes it: month-by-month, lifetime-long, and skeptical of any rule of thumb that hasn't been run through the math.