Question on WSIB Exemption Letter

I have a corporation with me as the only employee and i am hiring a contractor (also incorporated) for a client. The client has asked for a WSIB certificate or a certificate of exemption (if applies).

How do i go about it? Is it the same as Clearance on WSIB website? When i called WSIB, they said i should look at form 1158A, but the form has an Individual and the company. Since, the contract is between my corporation and the other one, not sure how this applies.

Also, the businesses are in IT Consulting.
Any advise is appreciated.