In a report published in 2013, the OBR said that more migrants are needed to
fund the rising cost of pensions, social care and the NHS.

If immigration runs at 140,000 a year, the national debt will reach around 99
per cent of the entire economy in 50 years time, the OBR said.

David Cameron has pledged to cut net immigration to “tens of thousands”,
though last year, the figure was still above 180,000.

The OBR’s calculations show that the closer Mr Cameron gets to his target, the
harder it will be for the British Government to balance its books in the
long term.

Without any immigration, the national debt will soar to 175 per cent of GDP in
50 years, the OBR says.

Mr Chote’s comments to the Treasury Select Committee come amid heated
political debate about immigration and its consequences, partly sparked by
the lifting of employment restrictions on Bulgarians and Romanians this
year.

The OBR’s assessment of the fiscal benefits of immigration is shared by some –
but not all – academic economists.

A study last year by economists at University College London calculated that
recent European immigrants pay £8.8 billion more in tax than they consume in
public services, the UCL paper suggested.

The Organisation for Economic Co-operation and Development, a think-tank, has
also suggested that Britain’s public finances are healthier in the short
term because of immigration.

However, other experts suggest that the beneficial impact of immigration on
the public finances could be temporary, since young and industrious migrants
could settle in the UK and become net consumers of public services as they
grow older and start families.

For example, the UCL study suggested that immigrants who arrived in the
Eighties and Nineties, then stayed and had children, now pay in only 85p for
every £1 of services they consume.