THE cost of setting up Scotland’s new benefits system has more than doubled.

Documents show the one-off investment required to create Social Security Scotland is now expected to be £651 million.

The Scottish Government previously estimated it at around £308m.

It comes after it emerged ministers may be forced to borrow money, dip into savings or make cuts to public services to pay for Scotland's rising benefits bill.

Officials said the cost of devolving benefits was unknowable when the initial figure was calculated in 2017.

Scottish Conservative MSP Adam Tomkins said: “Multiple benefits remain with the Department for Work and Pensions years after devolution.

“And we now have an SNP Government imposing yet more cuts on Scottish local government while its own budget goes up thanks to the consequences of UK spending.

“Having spent years criticising the UK Government over welfare policy, the SNP is now finding out just how hard it is to deliver a fair and affordable benefits system.

“But if the nationalists can’t even get the set-up costs remotely right, what chance do they have of administering payments properly?”

Scotland’s social security spending will rocket from £458m to £3.4bn this year, and will rise by a further £524m by 2024/25.

This change is largely driven by the Scottish Government becoming financially responsible for disability benefits, such as Personal Independence Payments and Disability Living Allowance, from April onwards.

Under the 2016 Scotland Act, Holyrood was given power over 11 benefits – roughly 15 per cent of social security spending north of the border.

A new business case for the social security programme said it is “developing and implementing systems to deliver over £4 billion of demand-led benefits each year, from 2024-25, safely and securely.”

It said the assets being created “will enable the delivery of social security benefits for decades to come”. It added: “The Scottish Government is making a significant investment to implement the systems required to do this for the future.

“Current plans indicate spending on implementation will total £651m from 2018-19 to 2024-25.

“This one-off investment in implementation will benefit the people of Scotland and will be used by future governments for decades.

“It represents less than 0.5 per cent of the estimated £150bn in benefits expenditure over the next thirty years.”

Scottish ministers will take responsibility for nearly all devolved benefits from April. However, some payments will continue to be delivered by the DWP on the Scottish Government’s behalf for the next few years.

Last week, the independent Scottish Fiscal Commission warned the demand-led nature of such a system meant its forecast costings “might be incorrect”.

It said Scottish ministers would have to find any extra money from borrowing, dipping into savings or reducing expenditure elsewhere.

Social Security Secretary Shirley-Anne Somerville said the Government is “investing in creating the infrastructure for a new public service for Scotland”.

She said: “Our new Scottish social security system is being built from scratch with dignity, respect and fairness at its heart.

“I am proud we are co-designing a service to meet the needs of in the people of Scotland now and for generations to come. And we are creating 1,900 jobs to support our work. We have met and surpassed our commitments to date. By the end of this parliamentary term we will have introduced 11 benefits that will help over 800,000 people in the next year.

“And by 2024 we will deliver 16 benefits and reach 1.8 million children and adults, and pay out an estimated £4bn.

“And we are ensuring we do not replicate the current DWP system which people find stressful, complicated and often inhumane.

“In 2020/21 we are committing £3.4bn in benefit payments to go directly to the people of Scotland who need it the most. Establishing our system, is a one off investment in implementation is less than 0.5% of total benefit expenditure over the next thirty years.

“Our steady state running costs will be around 5% of benefit expenditure, which is less than current DWP running costs – demonstrating that we are offering choice and value for money.”