The agencies try to pay as little taxes and no social contributions as possible. Exploring every loophole and actively creating some.
The really honest ones will give you answers.
The really good ones may have a system that actually works.
If anything is shady or debatable, the general concept is they do not pay and you get the penalty if foul play is called.
There is only one option, you get in touch with a licenced accountant of your own jurisdiction and pay them to research a tailored answer applicable to your personal circumstance.