> The hard part is knowing if you need to file a form.

In my experience, the form instructions tell you clearly when you should and should not file a form. They also clearly indicate which other forms are to be filed when you meet specific conditions (income limits, possession of specific other forms, etc.).

Granted, I don't run a business, nor do I have exceptionally complex finances, so there are a great many IRS form instructions that I have never seen. Because I've not see them all, I'd never say that every such form instruction is clear, but the ones I've encountered have been.