The review was revealed in a National Audit Office (NAO) report, published last week, into delivery of the programme, which is aimed at replacing six existing benefits with a single payment.
The report said the department is unable to continue its national roll-out of UC, currently being piloted in four job centres, until the service design and IT architecture is agreed.
It said: “Some assessments have commented that systems are inflexible or over-elaborate. The department is currently evaluating its options and does not yet have confirmed plans for its future IT system design and underpinning IT.”
The report added that limitations in the IT systems mean they cannot be rolled-out without further work and investment.
In order to reduce the complexity of the IT development work, the department is also considering scrapping its original aim to deliver most UC services online, even though this would increase spending on the manual handling of claims, the report said.
The NAO found that the DWP had spent £303m up to March 2013 on developing IT systems, and has already written off £34m of this.
Overall spending on UC implementation was £425m by the end of 2012-13, compared with a budget of £431m, but the report said the underspend was due to the department delaying plans to migrate claimants onto the new system.
It said IT costs are now expected to be £637m by April 2015 – 60 per cent up on the original estimate of £396m.
The report also found that reviews of UC had discovered “no evidence of the department actively managing its supplier contracts” and said it needed to “urgently get a grip” of the issue. It said that, on average, six project leads were given just three days to check 1,500 timesheets.
The report also said the problems meant that UC would not be introduced for all new out-of-work claims from October, as originally planned.
Called before the Commons to answer questions on the report, work and pensions secretary Iain Duncan Smith said that the programme would still be delivered on budget and on time by 2017.
Smith said: “The reality is that today’s NAO report shows there were problems in the running of this programme. I intervened when I discovered that and changed it, but I never expected to have to do that. When I arrived, I expected the professionalism to be able to do this properly.”
A DWP spokeswoman said the report did not cover recent improvements to the delivery of the UC programme.