Non-residence

The death of a close relative would be classed as exceptional circumstances as it is deemed "circumstances beyond your control" Sufficient time would be allowed to attend to the funeral arrangements and to deal with any immediate family requirements caused by the sudden bereavement, however NOT for duties as an executor as he could reasonably carry these out from outside the UK or appoint a professional to act for him.

I would be wary of pushing it though. If dealing with the affairs of his mother pushes him over the 91-days calculation then fair enough, however he should avoid wherever possible staying more than 183 days.

Yes. That would certainly fit the circumstance of exceptional. Your interpretation about the 183 is the same as mine, that it is essentially a strict rule, however there is some flexibility to the 4-year rolling average rule.

As a matter of interest how close to the limit was he before returning to the UK?

We have many non-resident clients and probably do an exceptional circumstances case about once a year.  The circumstances described above would be accepted by HMRC based on our experience. HMRC will also confirm a taxpayer's claim once the days have occurred before you have to do the SATR so if you write now they will reply ( such letters usually take 2-3 months ).

The longest number of days we have had accepted as exceptional circumstances was 113 days (did not take the individual over 183 in total) where a lady normally resident in the far east returned to the UK to give birth but due to medical complications was advised by her consultant not to fly. She stayed with her parents whilst recovering and returned abroad as soon as she had permission to fly (her husband and home was abroad). Due to the exceptional length we asked HMRC to confirm in writing that they agreed it was exceptional which they did.