How much tax would they pay if they were 100% British??  or how to raise £150 Billion for the UK economy!

I think the most useful next step is exactly that comparison. I have checked the latest available UK figures, including 2025 accounts and HMRC data.

The comparison we should make

I would use Apple, Microsoft, Google, Amazon, and then a large UK domestic company as the benchmark.

The important measures are:

UK revenue/turnover
UK reported profit
UK corporation tax actually paid
Corporation tax as % of UK profit
Corporation tax as % of UK turnover
What a 2%, 3% and 5% turnover tax would produce
Whether the turnover tax would actually be greater than the company’s reported profit.

There is already some striking evidence. Amazon says it generated over £30bn of UK revenue in 2025 and paid more than £1.3bn in direct UK taxes, but that £1.3bn includes employer NIC, business rates, digital services tax and other taxes — not simply corporation tax.

And Apple’s own UK tax policy explicitly says that profits derived from the UK but not attributed to UK activities are taxed in other Apple affiliates outside the UK.

That is precisely the distinction we need to capture.

One particularly revealing benchmark

The UK corporation-tax rate is currently 25%, but it is charged on taxable profit, not turnover.

So imagine:

Company UK turnover UK taxable profit Tax at 25%
Domestic UK company £10bn £1bn £250m
Multinational £10bn £300m £75m

Both have £10bn UK turnover, but the multinational pays only £75m because only £300m of the group’s profit is attributed to the UK.

That’s the structural issue your proposed turnover tax is trying to address.

And there is a very good real-world example: Apple Retail UK reported about £2.8bn turnover and £131.5m pre-tax profit. A 5% turnover tax would be approximately £139m — actually more than the company’s reported entire pre-tax profit. That shows why a blanket 5% would probably be too aggressive for some businesses.

But I think we can improve your original proposal

Rather than simply saying “5% turnover tax”, I would test three alternatives:

2% turnover levy
3% turnover levy
5% turnover levy

and compare those with existing corporation tax.

Then we can calculate the extra UK revenue and identify which companies would be hit hardest.

That would give us a proper answer to the question you’ve been pursuing in your earlier Microsoft/Oracle discussions:

Does the present UK corporation-tax system give large international companies a materially lower effective UK tax burden than comparable UK-owned businesses?

And importantly, we can distinguish legitimate international tax planning from actual tax avoidance/evasion rather than simply assuming that a low tax/turnover ratio proves wrongdoing.