reality check, 120k€/year already puts you in the top 1% of income earner in France. Past this point you should be satisfied with how much you've already earned and maybe starts caring more about the impact your job/company should have...
After taxes it's 80k which is NOT allot outside France (not even paris) and you are in the high-income class, you see when you want good people you have to pay them the right amount of money so they can pay everywhere for a good life. It's like saying, but 20$ a day is a perfect income for Morocco, why don't we have the best tech peoples around??
sigh... I assure you the top 1% earner of a high income per capita country enjoys a very high standard of living. A net income of 120k/y leaves with you with a real income of 94_080€/y (see sibling comment) or ~7840€/month when you're single. You'll have no problem renting a 30 sqm² for 1000€/month in a beautiful neighborhood in the center of Paris. Money isn't the problem, your "best tech people" are just too greedy.
And frankly, the recent backlash against big tech in relation to the ever rising compensation of SV people depicts a dark portrait of the "best tech people" around. This has more to say about the lack of moral standards in the industry than about the lack of incentives of the European Startups Ecosystems...
You live in Paris for the extensive catalogue of activities accessible : architecture, museums, monuments, unique places and restaurants, locus of power, demonstrations etc... all squeezed in 100km². The city is one of the most densely crowded area in the world for a reason.
I don't think I need to lecture you about the ubiquitous problem of housing prices in "world-class" cities.
Double downing on the reality check, 120k€/year is the top 1% of income earner in the vast majority of the World taking into account healthcare, retirement and education.
The price of new dwellings in Paris is 12863 EUR per square meter. How can you be satisfied with what you have earned when you still have to take a 20 year mortgage to get a decent home?
From £9.5k to £50k you pay 12% national insurance in addition to income tax, so it's really 32% not 20% tax.
Over £50k you pay 2% national insurance.
Your employer will also be paying 13.8% national insurance.
Once your income exceeds £100k you start losing your personal allowance at a rate of £1 for every £2 over £100k, so you have no personal allowance after earning over £125k. This means that your effective marginal tax rate between £100k & £125k is about 60%
I don't think such calculations are particularly useful, maybe about as much as Paul Graham's wealth tax "model". The reason is that tax codes are way more complicated than just nominal tax rates.
Did you know, for instance, that you taxable income is 90% of your real income [0]? So the 45% rate kicks in at a 175,340€ wage, not actually 157,806€.
Anyway, it does not matter because of the unusually large income splitting [1]. If both adults have a 157,806€ wage and say, two kids, the total income would be 315,612 with three fiscal shares, and thus would pay 3 times the amount of taxes owed for a 315,612/3 income (i.e. 105204€), where the marginal tax rate is 30%, not 45% [2].
Anyway, it does not matter either because the main income tax in France is not the "income tax", but the "generalized social contribution" (flat rate).
My point is not to write an essay on French taxation, but to show that simply comparing tax brackets and rates is useless, since the definition of "taxable income" is not the same between different countries, how brackets, rates and taxable income are used to actually compute the tax amount is not straightforward, there are many others taxes, and so forth.
[2] Amount of tax is number of n T(i/n), where i is income, T is the function which maps income to taxes owed and n is the number of fiscal shares. Because T is convex, n T(i/n) is less than T(i).
That's the problem you see?