Co-ordination between different welfare benefits has to be improved if Government departments are to achieve value for money, the National Audit Office has said.
A study found the Government spent £87 billion on means-tested benefits in 2009/10, 13% of total public expenditure.
The NAO said it is important that departments share good practice and learn from past experiences in the design of means tests.
"There is a lack of co-ordination of, and overall accountability for, means testing across Government." is said. "Departments are responsible for their own means-tested benefits and their impacts, but because means-tested benefits interact with each other it is important that there is co-ordination."
Amyas Morse, head of the NAO, said: "As Government prepares for the introduction of major proposed reforms in several programmes, it is vital that departments seek to understand some of the impacts of means testing that we have identified. They must then share this knowledge in order to learn from past experiences, so that risk to the taxpayer is minimised and benefits get to those who need them."
Margaret Hodge, chairman of the Public Accounts Committee, said: "For the poorest families in Britain means-tested benefits account for a third of their income. Getting this right is a hugely important issues. The report poses a range of important questions which the Public Accounts Committee will explore.Â
"We will want to understand how better value for money can be secured by looking at the benefit traps faced by the 700,000 people who enjoy less than 10p for every £1 earned. The report found it costs £47 to administer a Pension Credit claim and only £14 to process the State Pension which is not means tested. We will explore the administrative costs and the risks of fraud and error."
A Government spokesman said: "We welcome this report that highlights both the benefits and the challenges of effective means-testing. Universal Credit is being designed across departments with these issues in mind.
"It will strike the right balance between getting financial support to those that need it the most and making sure we incentivise work and better protect the benefits system from fraud and error."
The National Pensioners Convention said the report shows how "complex, expensive and inefficient" the means-tested benefits system is. General secretary Dot Gibson added: "It's time the Government realised that pensioners and means testing just don't mix. Older people find the whole process bureaucratic, difficult to understand and demeaning."