I'd translate "Beitrag" literally to "contribution", maybe add a "mandatory" as qualifier.
The key difference is that taxes are completely under discretion of parliamentary control, whereas the Rundfunkbeitrag is under discretion of the individual broadcast authority governance boards (which are too closely tied to politicians for my comfort, but that's another thing).
The key difference is that taxes are completely under discretion of parliamentary control, whereas the Rundfunkbeitrag is under discretion of the individual broadcast authority governance boards (which are too closely tied to politicians for my comfort, but that's another thing).