Compliant Employer

Hi, we are a small UK company whose employees are interested in occasionally working remotely from overseas for periods of maximum 3 months in a year. Their residence would remain in the UK, and all their work would be done online. In this situation, what obligations do we have as an employer? Do we need to withhold a different amount of taxes for them than usual? Do we need to pay a special insurance on our end while they work remotely from abroad? Or do they need to pay their own health insurance for the period they are working remotely from abroad? We think a lot of companies might have a similar question, so we really appreciate your answer as we work towards making it potentially possible for our employees to have this potentially great option.