James Cleverly introduced some serious restrictions on immigration, which Labour have upheld. Mahmood is going to introduce further restrictions. This has had the effect of reducing immigration substantially and forecast immigration (yes, even taking account the new method of counting.)
Immigrants, especially new immigrants, are disproportionate contributors to the UK's tax take, because they tend to be high earners and have no recourse to public funds. The low earners (who have mainly been blocked) are the bedrock of social care. The decrease in immigration has been more that the Chancellor planned for, so that leaves a substantial tax gap - at least £4bn and possibly £6.5bn annually.
Note this is from the Times, not a bastion of leftist thought.
So the question is, what do we do about this? Are you willing to pay higher taxes to pay for the shortfall? Should we lift restrictions on immigration to keep taxes lower?
Rejoining the single market or at least the customs union might help, but the same people who oppose higher taxes also oppose immigration and a closer connection the the EU
"Falling migration numbers could cost the chancellor as much as £7bn in fiscal headroom as he writes his first budget, The Times has been told. Government insiders believe that John Healey, who already faced an uphill battle to balance the books next month, is likely to have an even bigger challenge after immigration significantly undershot projections from the Office for Budget Responsibility (OBR). The Institute for Fiscal Studies think tank estimated last month that the success of Shabana Mahmood’s reforms, which have seen net migration cut to the low hundreds of thousands, could cost Healey some £4bn. Labour sources familiar with the budget process, however, said that the figure was now closer to £6.5bn. The OBR’s migration forecasts have been consistently higher than real numbers in recent years. Treasury officials, who have long expected Mahmood’s reforms to cause a hit to headroom, described the number as “pure speculation” but did not deny that Healey would have to contend with a larger funding gap than expected because of falling migration"
"At the same time, the OBR also observed that a ‘low migration’ scenario would – even after taking account of reduced pressures on public spending – push up borrowing by about £14 billion per year in 2028-29, considerably more than the cost of a 2p cut in National Insurance contributions, and raise the debt to GDP ratio – the government’s key fiscal target – by about 2.5%, or about £75 billion"
"In the short term, the biggest impact will be on social care, already struggling with workforce pressures and years of underfunding. Over the last two years, only a very large influx of migrant workers – 70,000 new starters in the last year – has saved the sector from an even deeper crisis. If the fall in visas issued is sustained, and there is not a large infusion of taxpayer funds, prospects are bleak."
https://www.thetimes.com/uk/politics/article/falling-migration-john-healey-headroom-zsw9rdcnr
https://ukandeu.ac.uk/immigration-is-falling-but-the-economic-cost-may-be-high/