Just tax the revenue in the country where the money changed hands. (The client's home) That's the taxable event. So, I think, for your case, Britain (UK)

How did the money change hands in Britain? The British person typed his CC number into a web form that routed to a server in the Cayman Islands that charged a bank in France. That bank in France will then demand repayment at the end of the month from the guy in Britain.

What was billing address on the invoice? The British company probably provided VAT number to buy VAT-free too.

The demand side actor is the driver of the transaction.

So if you had a completely Australian company selling stuff online, they'd be subject to US corporate tax for profit earned from American customers, French tax for customers from France, etc?

This seems complicated because unlike sales tax, corporate tax is based on profit at the end of the year. It's much more complicated than sales tax. Companies would have to handle corporate tax code for up to 195 countries.

Sure? Why not? I practice it wouldn't be 195. We're trying to fix a tax avoidance issue so we've to fix the money somewhere. Demand-side seems the right choice. I'm assuming there'd be some minimum threshold. Most companies are selling mostly at home. And if you want to play InternationalBigCo game it seems a reasonable burden to me.

To start with, how do you figure out how much profit this completely Australian company made in France? It's not their revenue from France, and all their expenses are in Australia. Does the company calculate expenses according to Australian law, or French law? Calculating expenses is complicated, and each country has different rules. You're effectively forcing companies to file full taxes in every country where they have customers.

If the company doesn't declare a profit in France, is France going to audit them? They have no presence in France.

Multiply this issue for every country where customers reside. This is bad for consumers. Companies are going to choose which markets are big enough for it to be worth the additional burden. If you're from Canada, too bad; we don't sell to Canadians.

Australia and France have similar tax rates. This doesn't have much effect on how much tax the company pays; just how much goes to France.

We have already have sales tax, which is a much simpler system that taxes revenue, not profit.

> If an American SaaS company sells a product hosted in Ireland to a company in Britain, where was that money "made"?

Britain. If corporations want to pretend that (for example) China has the authority to restrict what users in China see on foreign websites (cf recent Bing tank man mess, among many others), they can apply the same reasoning to tax liability.