I should have asked you, How do you know that they are really 1099 IC and not employees? How was this determined?
Just because they get 1099s mean that this is their correct classification. Classification is not detemined by either the Moving Company or the person, There are rules set by the state and the IRS. Penalties for misclassification are very severe.
Agreed, most vendors won't take checks and the participant has to write a check to the plan sponsor who then has to make the loan payments.
I'd say the clock starts when the check is received. If the participant is late it is not a failure to remit timely.