The Labour Party have issued a press release saying:
Initial costings by the Treasury show that George Osborne's proposal would raise a maximum of £650m, leaving George Osborne at least £2.9 billion short.
The Treasury's initial estimate, on best information available, is that just 15,000 current non-domicile residents have foreign income in excess of £62,000. Even cautiously assuming both a higher number and an increase in UK tax paid by individuals assuming domicile status produces an estimated maximum of around £650 million which could be raised from this measure.
Two things follow. The first is that the Treasury knows much more, and has done many more calculations on domicile than it apparently admits. It's time they put on record what they know.
The second thing is I have enormous difficulty believing that only 15,000 benefit by more than £25,000 from the domicile rule. My work suggests a figure nearer 30,000. The Treasury's data assumes that only investment income can give rise to the benefit. We know that's wrong. Other income can as well, especially when dressed up as gains or when disguised by trusts.
If they are right £375 million of the sum they suggest would be raised comes from the payment of £25,000 by each of the 15,000 non-doms using Osborne's rule. The rest of the £650 million, or £275 million would come from additional tax paid by the remaining 99,000 non doms they say there are. That's £2,777 each.
I don't buy that at all. That's under £7,000 of income each. That's just not enough to get into the tax accounting for this, to be candid. Only those with serious income bother to use this rule. It's implausible that the savings of most who do so are so small based on my own experience as a tax practitioner.
Of course, I may be wrong. But in that case why can't the Treasury just publish what they know rather than pay party political games with it? This is not a proper use of civil service time.