A senior employee is retiring but is willing to make himself available as a consultant over the next year or so. There will be no fixed hours, we can call him as and when and hopefully he will be able to help. If I've already made an ex-gratia payment to him as a retirement gift (thus avoiding tax/NI etc) will calling upon him as a consultant cause me problems with HMRC? He will invoice us for hours worked and he will no longer be on our payroll. Many thanks for any advice.