SCOTLAND’S population is forecast to shrink by almost a fifth over the next 50 years as its economic growth lags consistently behind the UK’s, Holyrood’s budget watchdog has said. 

The Scottish Fiscal Commission (SFC) also said Scotland faced “particularly acute" challenges because of its demographics.

The SNP said the predictions showed "the staggering cost of continued Westminster control" and underlined the need for independence.

Ahead of a full report on the tax and spending implications of Scotland’s population trends due out in the spring, the Commission issued a first set of projections today.

The body, whose figures inform Scottish Government spending decisions, projected Scottish GDP growth would average 0.9 per cent a year from 2028/29 to 2071/72.

This is 0.5 points less than the 1.4% GDP growth per year forecast for the UK as a whole.

Assuming low inward migration because of Brexit, the SFC forecast Scotland’s population would shrink considerably, with fewer working age people available to pay the taxes needed to support a growing elderly population.

Its projection is for Scotland’s population to fall from the current peak of 5.5million to 4.6m, a drop of 900,000 or 16% between 2022 and 2072, with low birth rate the key driver.

That compares to a 400,000-person increase in Scotland’s population since the late 1990s.

In comparison, the Office for Budget Responsibility predicts the UK’s population will fall by just 2% over the same period, from 67.1m to 65.9m.

If both predictions hold true, Scotland would be home to just 7% of the UK’s population by 2072, down from 8.7% in 1997 and 8.1% today. 

The total number of births in Scotland is projected to fall by 36% over the next fifty years, with 17,100 fewer births projected in 2072 than in 2022.

This is a result the population shrinking in combination with the low long-term fertility rate.

On current trends, the proportion of Scotland’s population aged 65 and over will increase from 20% today to 32% by 2072. 

However the proportion of working age people (16 to 64) in Scotland helping to fund services for those elderly people is forecast to decline from 64% today to 56% by 2072.

The proportion of under-16s in Scotland is due to fall from 16% today to 12% by 2072.

The SFC said this implied tax revenues in Scotland per head were likely to grow more slowly in Scotland than in the rest of the UK, meaning less income tax for the Holyrood budget.

The SFC report said: “These demographic changes will have implications for the economy and income tax revenues. There will also be implications more broadly for Scottish Government funding and spending in the future.”

It added: “Our projections show that Scotland faces similar though more pronounced challenges to other high-income nations and to the UK in terms of ageing population.”

The report also predicted that Scotland’s population would be on average 7.6 years older in 2072 than it is currently, compared to 6.1 years in the UK.

Commission Chair Professor Graeme Roy said: “While Scotland is no different from most high-income economies in facing demographic pressures, those facing Scotland are particularly acute.

"Our fiscal sustainability report next year will explore how these will affect the Scottish Budget in the future. Politicians and those delivering public services will need to consider how to respond to these future fiscal pressures.”

Liberal Democrat MSP Willie Rennie said: "These stark figures show that entire industries are likely to find themselves in peril, from social care to fruit picking. 

“The Scottish Government must do better at making Scotland a more attractive place to live and work.

"With an ageing population, Scotland and indeed the whole of the UK needs immigration in order to flourish.

"That’s why arbitrary Conservative immigration plans are so misguided. We run the risk of starving our economy and NHS require of the talented people they require."

SNP MSP Michelle Thomson said: "These projections show the grim reality that Scotland faces as a consequence of a future under Westminster control - underlining how vital it is for people to have a choice of a better future as an independent country.

"Whilst Northern Ireland's economy reaches a 15 year high as a part of the world's largest single market, Scotland is being left to suffer the impact of Westminster and its damaging Brexit obsession - leading to a predicted 50 years of economic decline and stagnation for Scotland, despite Scots overwhelmingly voting to remain in the EU and the single market.

"This is not the future Scotland wants or deserves, and that is why people voted to have the choice of a future where we can build a better, more prosperous and independent country away from the failing Westminster system and impact of continued Brexit chaos."