What actually changes for tax, NI and take-home
UK contractors often hear “Outside IR35” and “umbrella” in the same conversation and still cannot tell what that means for money in the bank. This guide explains the practical difference, without pretending to decide your IR35 status for you.
If an engagement is Outside IR35, many contractors operate through their own limited company. The company invoices the client or agency. After allowable costs and Corporation Tax, profit can be extracted as a mix of director salary and dividends.
That structure can be tax-efficient compared with pure PAYE, especially at higher day rates, because dividend tax and Corporation Tax interact differently from employment tax and National Insurance. It also brings obligations: company accounts, filings, and payroll if you pay a salary.
An umbrella company employs you for the assignment. It invoices the agency or client, takes a weekly margin, runs PAYE, and pays you a net salary. Employer National Insurance is part of the employment cost and usually reduces what is left for you compared with a well-run limited company on the same headline rate.
Umbrellas are common when a role is Inside IR35, when a client insists on PAYE, or when someone does not want to run a company. “Compliant” matters: you want transparent deductions and a margin you understand, not promises that ignore employer NI.
Side-by-side calculators often show a higher annual take-home on the limited company side for the same day rate and working days. That is not magic and not a guarantee for every person. It reflects different tax treatment: employment costs on the umbrella path versus Corporation Tax plus dividend tax on the company path, plus expenses that may be claimable in the company in ways that do not map one-for-one onto PAYE.
The gap widens or narrows with day rate, number of working days, expenses, umbrella margin, pension contributions and student loans. That is why a single “average” figure is less useful than a model you can adjust.
IR35 is about the nature of the engagement—control, substitution, mutuality of obligation and related factors—not about which spreadsheet produces a higher number. A calculator cannot declare you Outside or Inside IR35. Getting status wrong can be expensive.
Use status determination processes and professional advice for the engagement itself. Use a take-home comparison only to understand the financial shape of each operating model once status or commercial constraints are known.
If you want a fast starting point, open the free calculator on this site, try the preset day rates, then replace the margin and expenses with your numbers.
Compare Outside IR35 (limited company) and umbrella take-home with your own day rate, days, expenses and margin.