Rebate cash from credit cards

Hey Matt, Big fan of you both!!!
Can I use the rebate cash from both my personal and business credit cards to fund a SD custodial account and or in my case the qualifying SD entity that manages my company trust T and R retirement accounts at my bank. And is that tax free on its transfer to those accounts.
To me this could be a very useful small business tool/practice and permission if the system is setup properly.