Presume you’re thinking of the teleworking tax liability? Hmm, not completely sure, perhaps I can offer an (alternative) opinion from the defense POV? The France tax liability turns on the centre of economic and social interests - the economic interests remain in the UK, the social interests (family) are in France but temporarily, as the movers would argue. No CDS. Fixed time limited accommodation, not owned. Maison principal in UK. (not rented?)
I’d have to defend kids being in school is not an indicator of permanence, merely a result of temporary stay. My biggest problem for the defence might be that sticking your kids in school is a sign of permanence.
And the france tax code does state residence is availability of accommodation, exclusive to oneself - a bit silent on permanence as far as I recall.
I think if pursuing the defence further I’d have to go and research some case law here (I’m not). If none, then likely the Impot aren’t going to be bothered, even assuming they are alerted. If the impot do take up the case, and there is no case law, then the case law will be formed.
The breadwinner could even just stick to UK/France ‘frontaliering’ and that would be more case law to sort out.
Social sec - entry to healthcare - I have no idea how. But maybe the people would do private healthcare. I wonder how @vero ‘s friend with he kids managed that - could be an insight.
I also have a lot of sympathy for the moral cause raised by @JaneJones - one is using France resources, why not contribute? Though there again is the difficulty of persuading employers, etc to go with the added bureaucracy.
There is I presume no ‘temporary’ tax resident status, so permanence would all turn on the ‘centre of economic / social’ interests.
better tag @lauriel18