Your problem is with the actions that they're lobbying for, not the lobbying itself. If H&R Block instead lobbied for clean water for all US citizens, you wouldn't have an issue with that.
It is ok to think that the cause (complicating the tax code) is wrong, but the methods (lobbying) are ok.
I'm not sure how you can seperate the two. You say that lobbying is never wrong but if "the actions that they're lobbying for" are wrong it would seem to me that the lobbying in that instance is wrong as well.
It is ok to think that the cause (complicating the tax code) is wrong, but the methods (lobbying) are ok.