>No, it really isn't.

You must not be reading hard enough.

"To the extent that taxing something results in less of it (whether income or consumption), taxing consumption instead of income should encourage both work and capital formation, which increases economic growth, while discouraging consumption.[3][4] Secondly, the tax base is larger because all consumption is taxed. "

"Many economists and tax experts favor consumption taxes over income taxes for economic growth.[26][27][28] "

But my question from the outset was about the rationale for taxing both income and consumption, which I stated plainly and repeatedly. You're pointing me at arguments for a situation that doesn't exist in the present.

Perhaps you're the one who should read more carefully.

>But my question from the outset was about the rationale for taxing both income and consumption

Diversification and/or anti-evasion? As per the wikipedia article consumption taxes are better because they favor investment rather than consumption, but it's pretty easy to evade by smuggling the money out of the country. This is very easy to do, especially if you need to transfer money of a country for a "business venture". Income taxes are also evadeable by taking money under the table. Taxing both basically makes it impossible to evade taxes.

> But my question from the outset was about the rationale for taxing both income and consumption

There is no such rationale: its a compromise between ideologically opposed forces with diametrically opposed goals for society, not a coherent policy with an integrated rationale.

> To the extent that taxing something results in less of it (whether income or consumption), taxing consumption instead of income should encourage both work and capital formation

That's...kinda silly on the "work" part as an economy-wide statement, and the way that it is true selectively about work and also true about capital formation is...well, there is a reason that people who make this argument are vague and handwavey about how it works.

Taxing things doesn't just magically reduce them in isolation, it reduces them by reducing the net marginal value realized from each marginal increment. But taxing consumption reduces the marginal value of work exactly the same as taxing income, because the marginal value isn't realized by getting a paycheck but by spending the paycheck on consumption; it discourages work, rather than encouraging it. At the same marginal rate, a consumption tax reduces the incentive for additional work just as much as income tax.

But, ät the same marginal rate" is key: VATs are essentially regressive, whereas modern income taxes tend to be progressive, sometimes fairly sharply so on "regular" income, counteracted slightly for the capitalist class by counting the kinds of income they have as eligible for favorable rates.

So, at any given overall revenue level, a VAT is going to have higher effective marginal rates for lower-income workers and lower effective marginal rates for higher-income workers than a politically palatable income tax, and that: that it reduces the incentive and reward for work for lower income workers while raising it for higher-income workers (whose work is also higher-return for the capitalists capturing most of the value produced by work) is what they are referring to when they say it encourages (some) work and favors capital formation. Its not that it coincidentally makes it harder for lower-end workers to get ahead by worker and pushes rewards up the scale both within the working class but also out of that class into the petit and haut bourgeois classes, but that is indeed the exact effect that those "economists and tax experts" are praising.

It's also not a coincidence that the "economists and tax experts" tend themselves to be high-income workers or petit bourgeois, as well.