The mandatory paperwork in case of freelancer is quite minimal effort. I have an accountant to whom I need to provide material. Currently in the paper form, but soon switching to electronic. Gathering the material takes about 2 hrs/ month.

Billing takes 5 minutes (I use web application called Zervant) and checking that the payment is received takes few minutes.

Then there are "random" stuff like updating insurance, meeting people (few times per month) etc.

Not that much stuff really.