Employee is a director
The employee will need to either provide you a copy of their P45 or complete the HMRC new starter checklist (ideally both). If newither are provided the employee will be put on a basic rate tax code.
The HMRC new starter checklist can be found here:
Web version - https://www.tax.service.gov.uk/guidance/check-what-information-to-give-your-new-employer/start/where-you-live
PDF - https://assets.publishing.service.gov.uk/media/69959214bfdab2546272bf04/Starter_checklist.pdf