RDRM11560 - Residence: The SRT: Work tie
The individual will have a work tie for a tax year if they do more than 3 hours of work a day in the UK for at least 40 days in that year. It does not matter whether the days are continuous or intermittent.
However, there are special rules for what counts as 3 hours work for individuals who have a relevant job - refer to RDRM11800 for more information.