RFIG20810 | Statutory Residence Test (SRT): Days spent in the UK: Deductible travel expenses for tax purposes
From HM Revenue & Customs · Residence and FIG Regime Manual
Deductible travel expenses for tax purposes are those where the expenses would have been deductible when calculating:
an individual's earnings from employment and the travel would have fallen under the following categories:
the travel expenses were necessarily incurred in the performance of the duties of their employment
the travel was required for necessary attendance in the performance of their duties of employment
the travel was required for travel between group employments
the travel was travel between employments where the duties are performed abroad.
OR
the expenses would have been deductible when calculating the profits of the individual's trade.