MPs and campaigners have urged the Government to go further in reforming benefits for disabled people after ministers published their response to a major review.
The Department for Work and Pensions has pledged to make recording assessments for Personal Independence Payment (PIP) a standard part of the process.
This is one of the recommendations the Government has accepted after an inquiry by the Work and Pensions select committee into PIP and Employment and Support Allowance (ESA).
However, ministers rejected other recommendations in areas such as collecting evidence and ensuring claimants are sent a copy of their assessment report.
The Department for Work and Pensions said the committee's inquiry showed that assessments worked well for the vast majority of people, and it was committed to putting transparency at the heart of the process.
Labour MP Frank Field, chairman of the select committee, said recording PIP assessments as standard was "a tremendous step forward".
"The process relies on trust, and our inquiry found it sorely lacking. This move should go a long way to restoring trust and driving up the quality of assessments," added the former welfare minister.
"But the response falls short in several areas. For example, we think claimants should always receive their assessment reports without having to ask, and we are concerned that the Government lacks the levers to get value for money out of its private contractors.
"This response marks the start of another stage in our work on PIP and ESA - we will use House of Commons debates to push the Government to go further in support of disabled people."
Nearly 3,500 people provided evidence to the committee about their experience of PIP and ESA, in what Mr Field said was an unprecedented response.
MPs found that for at least 290,000 claimants of PIP and ESA, 6% of all those assessed, the right decision on entitlement was not made first time around.
There was concern over the cost of the appeals process, with Press Association research showing £108.1 million was spent on direct staffing costs for ESA and PIP appeals since October 2015, with the Ministry of Justice spending a further £103.1 million on social security and child support tribunals in 2016/17.
The private firms carrying out PIP assessments have been paid £824 million since the benefit was introduced in 2013, according to figures obtained by the Independent.
The committee's final report in February expressed concerns over assessment reports "riddled with errors and omissions" and that public contract failures had "led to a loss of trust that risks undermining the operation of major disability benefits".
It also suggested the assessments for PIP and ESA may be better delivered in-house.
In its response, the DWP said the quality of both PIP assessments and the work capability assessment for ESA claimants was improving year on year and its "use of contractual levers over the last contracts has led to consistent improvements across both PIP and ESA".
In response to the select committee report, the DWP is to commission independent research to improve the application forms, which Mr Field has dubbed "gruelling".
However, ministers rejected a recommendation to send claimants copies of their assessment reports as standard, saying only that they would improve communications to ensure people know they can request a copy.
The Government also rejected calls for a "checklist" system for assessors to monitor what evidence they were using in their decisions, saying all supporting evidence is already recorded and attached to claims.
Charities Disability Rights UK and the MS Society welcomed the move to record assessments, but urged the Government go further.
"Overall, the current assessment providers offer poor value for money for the taxpayer and we urge the Government to consider very seriously the option of returning the assessment process in house, given the contracts are up for review," said Philip Connolly, policy manager at Disability Rights UK.
"But we have to remember that PIP and ESA are not well designed benefits, and fail to meet the needs of many disabled people.
"Changes to the assessment process for the better are welcome, but there are wider issues which need to be addressed."
Genevieve Edwards, director of external affairs at the MS Society, added that "a lot more needs to be done before we see a welfare system that makes sense".
She said: "We're particularly concerned the Government won't make improvements around how healthcare professionals can consistently provide evidence.
"Without this, assessors don't have enough knowledge about MS and this is causing many people to be denied what they are rightly entitled to."
A Department for Work and Pensions spokeswoman said: "As the committee highlights, assessments work well for the vast majority of people.
"But one person's poor experience is one too many, and we're committed to continuously improving the process for people so that they get the support they need.
"We'll continue to take forward our actions to improve assessments, with an emphasis on promoting transparency and ensuring people get the right decision, first time round."
Labour's shadow work and pensions secretary Margaret Greenwood said: "The Government is failing sick and disabled people. This response falls far short of the urgent action needed to end the unnecessary stress and anxiety being inflicted through both the ESA and PIP assessment processes.
"Under private contractors these processes are getting worse, not better, often damaging the health and well-being of the very people who need support.
"The Government should scrap the current assessment regime, put an end to the privatisation and work to deliver a social security system in which people can have confidence.
"Labour will replace this failing system with personalised, holistic support, responsive to individual needs."
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