Open Source Tax Software

French tax law is actually very complicated, I guess like just about everywhere. If your only revenue is your salary, and you don't have a lot of deductibles, all you need to do is sign the form (electronically). But if you are self-employed, it is highly recommended to hire an accountant if you don't want nasty surprises if you get audited.

Most people though just use a tax preparer at something like H&R block. A little searching indicates there's roughly 60k to 80k jobs like this in the US, and they earn (at least at H&R Block) about $16 per hour, and only for about 3 months a year. A small # of tax preparers with a bit more training & experience may provide other financial services in the off-season or assist small business with quaterly filings or bookkeeping.

Overall though, you're not talking about much of an industry collapse in terms of people employed. The ones that work in that area year-round will lose some extra hours. The ones that don't, having some experience in finance, might seek further training to get a higher level job of that sort (maybe become an actual accountant) I don't think it should be considered a barrier to ending regulatory capture within this area.

Apart from that, a few software products would collapse, losing most customers, retaining the ones that legitimately needed advanced guidance. And the company would probably have to charge the more for it, and possible compete with actual accountants on price in that respect.

But I don't think "industry collapse" is correct.

In the UK the government communicates your tax code to your employer payroll department to tell them how much tax to withhold on your earnings (taking account of tax credits etc.) Banks have to withhold the basic rate of tax (higher rate tax payers must file, but that already excludes 90% of tax payers from worrying about it.)

In the US the system seems similar except the government doesn't let your employer know how much tax to withhold so you fill in a form for your employer with the information that gets it mostly but not quite right (so long as you don't switch jobs that year!) Filing taxes as a regular employee ends up being substantially more complex than filing taxes as a self-employed person in the UK where the government provides an online system much simpler than that provided by the tax filing companies in the US (otherwise print and mail several different PDF forms and do the math yourself, fortunately if you get it wrong the IRS already knows what you owe so at that point they'll just point out the corrections and tell you what you owe...) And this beurocracy is of course all doubled because states have their own completely separate set of rules.