Idk... for good starters, I'd ask ye this
I'd rather ask how it is not capitalist
Is it capitalist and hegemonic
Does this federation have a system of unequal exchange and resource exploitation of one place to another, the core, essentially, with the majority of the federation being an large mass of desperate wage and salary laborers, once self-sufficient peasants, in the resource-rich place of the periphery, under the guise of "investment"?
Does this federation love to lend and privatize foreign economies, and cut social spending, a la IMF, in order to dominate the latter's economy?
Does this federation have a policy of CAPITALIST settler-colonialism, based on classical-liberal style property rights and genocide of the indigenous people?
If this is all merely in the past of class struggles and national liberation movements, and the federation has fought and abolished such forms of exploitation, yay
To check if its communist, in the more modern form {there is such thing as primitive communism}, however:
Does this federation wrecked out any chance of capitalist and liberal restoration, due to past 'authoritarianism'?
Does this federation work without the use of money, any proprietorship, social class, and the force of government, but instead with collective ownership of major assets and modern cooperative values or 'ideology' being casually accepted as the norm, instead of as an old-fashioned ideology or academic subject?
This is to ensure that Communism is dominant, as to be practically 'Communist', in such a federation
Does surplus value, from labor, go into the needs of the people, even in its 'authoritarian' fetus defensive form, instead of going towards any capitalist profit or landlord's rent, or any past economic mode of production?
Note: Personal property, such as watches and purses, do not count as private property, unless you're using it to make into an asset, like a steam engine, to run a metro-train system, or a collection of buildings, to take rent upon