The real answer is that it costs the business $0 because the after tax income of the business owner does not effect the inherent profitability of the business. Only the demand for its product or services and its ability to fulfill it do that. This argument that its going to hurt small business is BS. It's going to close a loophole that shouldn't have existed in the first place and business owners who've depended on it are understandably upset. But they can't defend the loophole so they try to make it about everything that isn't about.