Inside vs Outside IR35: The Financial Difference

The financial difference between working inside and outside IR35 is significant — typically 20–30% of contract revenue at standard day rates. Outside IR35, you retain access to the salary and dividend structure and keep corporation tax advantages. Inside IR35, the same income is treated as deemed employment income, taxed at employment rates, with almost none of the efficiency available.

How the tax treatment differs

Outside IR35: the optimal structure

Your company receives the contract revenue. You pay yourself a salary of £12,570 (no income tax, employer NI of ~£1,136) — CT-deductible. Corporation tax is paid on remaining profit (19% at small profits rate). You then extract remaining profit as dividends, taxed at 8.75% within the basic rate band. The combined effective rate on money you extract from the company is typically 25–30%.

Inside IR35: deemed employment income

The fee-payer (client or agency) deducts PAYE income tax and employee NI from your payments before they reach your company. Your company receives the net amount. The company cannot then pay you dividends from that income — it has already been taxed as employment income. The effective rate on inside-IR35 contract income is typically 35–42% depending on your total earnings.

Take-home comparison by day rate (2026-27)

These are approximate figures assuming: outside IR35 uses £12,570 salary + basic-rate dividends; inside IR35 uses standard PAYE with personal allowance. Use the IR35 calculator for precise figures based on your exact situation.

Worked example: £450/day outside vs inside IR35

Outside IR35 (£99,000 revenue):

• Salary: £12,570 (no income tax, employer NI £1,136)
• Company profit after salary/NI: £85,294
• Corporation tax (19%): £16,206
• Distributable profit: £69,088
• Dividends taken to fill basic rate band (£37,700): dividend tax £3,255
• Remaining £31,388 retained or extracted at higher rates
• Take-home (extracting everything): ~£66,000

Inside IR35 (£99,000 revenue):

• Deemed employment income: £99,000
• Personal allowance: £12,570 (no tax)
• Basic rate tax (20%) on £37,700: £7,540
• Employee NI (8%) on £37,700: £3,016
• Higher rate tax (40%) on remaining: varies
• Take-home: ~£55,000

Annual difference: ~£11,000

What rate uplift is needed inside IR35?

To match the same take-home inside IR35 as outside, you generally need a 20–25% rate increase. At £450/day outside, you would need approximately £540–£560/day inside to achieve equivalent take-home pay.

Whether clients accept this depends heavily on market demand for your skills and whether there are outside-IR35 alternatives. In markets where contractors are scarce, rate uplifts of 15–25% are common. In commodity markets, clients resist uplifts and contractors absorb the cost.

Pension: the main mitigation inside IR35

Even inside IR35, your company can make employer pension contributions. The deemed employment income calculation allows for pension contributions to be deducted before the PAYE calculation in some structures. Your accountant can advise on the exact mechanism, but the principle is: divert profit into pension before it becomes deemed employment income, reducing the taxable base.

This is the single most effective way to reduce tax inside IR35. A £20,000 employer pension contribution inside IR35 can save £8,000–£10,000 in combined income tax and NI compared to taking that as income.

Umbrella company as an inside-IR35 alternative

Many contractors inside IR35 use an umbrella company rather than running their own limited company. An umbrella company employs you directly, handles PAYE, and pays you a net salary. The advantages: zero admin, no company to maintain, no risk of getting IR35 wrong. The disadvantage: you lose any tax planning flexibility and typically pay a weekly or monthly umbrella fee (£15–£30).

For contractors with only inside-IR35 engagements, umbrella is often the simpler and lower-cost option. For contractors with mixed inside/outside engagements, keeping the limited company makes more sense.

Common mistakes

• Not negotiating a rate uplift — many contractors simply accept the inside IR35 determination without negotiating. The financial gap is large enough to make the conversation worthwhile.
• Ignoring the pension option inside IR35 — the pension lever is the main mitigation available, but many contractors don't use it because they assume IR35 removes all planning options.
• Continuing to pay dividends from inside-IR35 income — money received by the company as deemed employment income has already been taxed. Taking it again as dividends creates double taxation. Seek specific advice on the correct treatment.