I've no idea what (if anything) you would accept as evidence. Here's the first paragraph of the Wikipedia page on communism; feel free to check that the [...]s don't hide anything that changes the meaning.

> [...] communism [...] is a[...] ideology and movement whose ultimate goal is the establishment of the communist society, which is a socioeconomic order structured upon the common ownership of the means of production and the absence of social classes, money, and the state.

Does a universal basic income cause, or require, common ownership of the means of production? Nope. The means of production stay largely in the hands of businesses (or, as the communists might say, of Capital). Does it involve the absence of social classes? Nope. Successful lawyers (say) will continue to have much, much more money and much higher social status than anyone who's largely dependent on basic income. Does it involve the absence of money? Nope. It depends on the continued existence of money. Does it involve the absence of the state? Nope. It depends on the continued existence of the state.

Well, who cares what those pinko loons at Wikipedia say? Communism is whatever they had in the Soviet Union. How about that?

Well, in the Soviet Union they had a centrally planned economy where the government told factories how many of everything to make, etc. Does a universal basic income cause or require that? Nope. Businesses continue to decide what to make and what to sell at what prices; individual consumers continue to decide what to buy. ("But a basic income would require a big government!" Well, kinda, in that the government would be taking in more tax and handing out more money. But that's got nothing to do with central planning. A basic income wouldn't mean that the government would do more of the work; if anything, it should be less because the BI would replace a bunch of other more complicated benefits that require more administrative work to make sure they're going to the "right" people.) In the Soviet Union they had a totalitarian state with secret police, gulags, etc. Does a universal basic income require that? Nope. Obviously. The Soviet Union had undemocratic politics where the Communists were always in power. Does a universal basic income require that? Nope. Obviously.

"Communism" does not mean the same as "anything vaguely leftish that I don't like".