Well, if she invoices the fee to her company, then any salary income taken from that is of course subject to PAYE and NIC (employers and employees). I guess your question is can she take all the fee out in dividends? If she did, that would almostly attract the attention of HMRC since that was the very thing that IR35 was established to stop. She could take part of it as salary, but the issue is how much and is this a one-off situation or part of the irregular income of a trading operation.