I think it is, at some level. The definition of socialism, especially when not contrasted with social democracy, Democratic socialism, or communism, can be very vague, but the idea that a portion of labor is shared back feels like it's in line with the spirit.

From Miriam Webster:

"any of various egalitarian economic and political theories or movements advocating collective or governmental ownership and administration of the means of production and distribution of goods"

Taxes are just a way of taking some of the value of goods and redistributing them. Governments enforcing taxes are them getting involved with the administration of said goods.