Despite some high-profile failures, such as the ‘reset’ of the controversial Universal Credit programme, the NAO’s Welfare reform: lessons learned report said the DWP had continued to make progress in major programmes and was overcoming operational challenges.

But it urged the department to think more clearly about how its proposals would work in practice.

Among the reforms examined were the implementation of the £26,000 household benefit cap as well as the introduction of pensions auto-enrolment and the Work Programme to tackle unemployment.

Overall, the department did not have a sufficient understanding of its portfolio of programmes or its capacity to deliver them, the report stated, while it had thought too late about the indicators it needs to understand progress and performance.

Often the department had a clear, high-level vision that it wanted to implement, but it needed to think more strategically about how such reforms will work in practice.

NAO head Amyas Morse acknowledged that any large portfolio of reforms will run into problems, and highlighted the department had shown a resolute approach to dealing with them.

‘However, we think it has relied too much on dealing with difficulties as they emerge rather than anticipating what might go wrong,’ he said.

‘As a result it has had to learn some hard lessons with significant financial and human costs.

‘It is important that the department use these hard lessons to improve how it manages change and anticipates risk.’

Responding to the report, a DWP spokesman said that the reforms being taken forward by the government ‘restore fairness and common sense to the welfare state whilst guaranteeing a safety net for the most vulnerable’.

He added: ‘This department has one of the most ambitious reform agendas across Whitehall and has successfully delivered welfare reform, while cutting overall costs – as this report acknowledges. While this report looks to the past, we are busy looking ahead, continuing to deliver reforms safely and incorporating lessons learned as we have always done.

‘Delivering change on this scale is a challenge, but this government is committed to delivering a benefit system that is fairer for all.’