Inside vs Outside IR35: The Real Financial Difference

The IR35 status of your contract has a direct and substantial impact on your take-home pay. Understanding exactly where the difference comes from - and how large it is - is essential whether you are negotiating a new rate, assessing a status determination you have received, or deciding whether to challenge an inside-IR35 decision.

How outside IR35 works financially

When you operate outside IR35, you receive your client fees into your personal service company (PSC). You then typically pay yourself a low salary - often around the personal allowance or National Insurance lower earnings limit - and extract the remaining profit as dividends.

The efficiency of this structure comes from several places:

• Low salary means low NI. You pay employee NI only on salary above the primary threshold (£12,570 in 2026/27). By capping salary at this level, employee NI is eliminated or minimised.
• Employer NI is modest. Your PSC pays employer NI at 13.8% on salary above the secondary threshold (£5,000 in 2026/27). On a salary of £12,570, this is a relatively small amount - and note that solo-director PSCs with no other employees cannot claim the Employment Allowance, so this cost is real.
• Dividends are taxed at lower rates than salary. Dividend tax rates are 8.75% (basic), 33.75% (higher), and 39.35% (additional) in 2026/27 - lower than the equivalent income tax rates of 20%, 40%, and 45%.
• Corporation tax is paid on business profits. Your PSC pays corporation tax (25% main rate; 19% small profits rate on profits up to £50,000) before distributing dividends. This is already accounted for in the dividend strategy.

How inside IR35 works financially

When a medium or large client determines you are inside IR35 under the Chapter 10 off-payroll rules, the financial picture changes considerably. The fee-payer - usually an agency - calculates what HMRC calls the “chain payment” and:

• Deducts employer NI from the gross payment (at 13.8% on amounts above £5,000) - this comes off the top of your rate before you see any of the money
• Deducts income tax (PAYE) at the appropriate rate on the remainder
• Deducts employee NI (8% on earnings between £12,570 and £50,270; 2% above)
• Pays the net amount to your PSC

The result is that the employer NI - which an actual employee would have covered by their employer out of a separate payroll budget - is effectively borne from your day rate. This is the single biggest driver of the inside-versus-outside take-home gap.

The compound effect over time

A gap of £5,000-£10,000 per year might not sound alarming on a single contract, but over a five-year contracting career it represents £25,000-£50,000 of after-tax income - money that would otherwise be available to invest, pay down debt, or fund retirement savings. That compound effect is why getting your IR35 position right matters well beyond any single engagement.

Many contractors who receive an inside-IR35 determination choose to negotiate a rate increase to compensate. This is a legitimate approach - the client's true cost of the engagement includes employer NI whether you are inside or outside IR35, so structuring it as a higher gross rate is commercially reasonable.

The day rate sweet spot

The financial advantage of outside IR35 is not uniform across all day rates. At lower rates, where most income falls into the basic rate band, the difference between 8.75% dividend tax and 20% income tax is proportionally larger. At very high rates, more dividends are taxed at 33.75% - close to the 40% higher rate - so the gap narrows somewhat.

The biggest single factor remains employer NI. At any rate, being forced to absorb 13.8% employer NI from your gross fee is a significant levy that directly reduces take-home.

What to do if you are inside IR35

Receiving an inside-IR35 Status Determination Statement is not the end of the conversation. You have options:

• Raise a formal dispute. Medium and large clients are required by law to operate a 45-day disputes process. If you believe the determination is wrong, challenge it with evidence. A well-documented case referencing control, substitution, MOO, and BOOA can change the outcome.
• Negotiate a higher rate. The inside-IR35 tax burden falls on the fee-payer chain before reaching your PSC. A rate increase can partially or fully offset the difference.
• Consider umbrella employment if the administrative burden of running an inside-IR35 PSC is not justified by the rate.
• Review your working practices. If the determination was based on actual working arrangements rather than just contractual terms, working practices can sometimes be restructured to genuinely support an outside-IR35 position - and then a re-assessment requested.