I. A hiring party may voluntarily contribute funds to an independent contractor's portable benefit account. II. Contributions may be made using funds withheld from compensation owed to the contractor, provided that: (a) The withholding is expressed in a written agreement; (b) The agreement is clear, unambiguous, and prominently displayed in the contract; (c) The contractor affirmatively opts in to the withholding; and (d) The contractor may opt out of such withholding at any time.