If I have a client that opened a RIA Channel 529 plan with me and I have no other of his assets under my control how could I charge my quarterly fees? Do the plans send me a check for my percent of the fees on a quarterly basis? Do I have to charge him directly?
Generally, you would have to bill the client directly unless the custodian who holds the other accounts you advise on is the same as the 529 custodian. Your client should have signed an advisory contract with you and the contract would stipulate how and when those fees are collected (i.e. whether they are monthly/quarterly and whether they are direct bill or collected from other accounts you manage). It would be a good idea to review your advisory contract to ensure the client agreed to a direct bill scenario.
In cases like this, I send electronic bills if the amount is slow and ask them to pay through paypal or google wallet.