Thousands of people could get a surprise payment of as much as £12,000 from the DWP – and there are 21 health conditions that are most likely to get the cash, it has been revealed.
The Department for Work and Pensions has already paid out £18million to people who lost out because of a legal error relating to the points it awarded for Personal Independence Payment (PIP).
PIP is a benefit meant to help people with a long-term physical or mental health condition or disability.
The DWP error meant some claimants got lower PIP payments, while others were refused PIP altogether because their points weren't high enough to qualify.
One man received a huge award of backpay when the DWP finally agreed to review his case.
The claimant, who has a severe mental health condition, felt he should be eligible for a back payment of PIP, according to Birmingham Live .
If you have daily living and/or mobility needs because of a mental health condition, you may be eligible for PIP
After a long battle, including two requests to review his case and an attempt to take the DWP to a tribunal, officials agreed to carry out a 'mandatory reconsideration' and awarded him £12,000 in backpay.
Now, the social security advice site Benefits and Work has identified a list of conditions that DWP documents say are most likely to be eligible for backpay.
Have you received a lump sum from the DWP because of a PIP error? Get in touch: Mirror.Money.Saving@mirror.co.uk
The key conditions are:
Benefits and Work said: "It should be stressed that this was just the DWP’s prediction of who is most likely to be eligible. Just because your condition is not listed here, that does not mean that you are not entitled to a back payment.
"Nor, if your condition is listed here does it mean that you are going to get an award. It is clear that the DWP has chosen to make very few awards indeed."
The DWP has paid out £18million so far to PIP claimants who lost out because of the error, but might owe as much as £3.7billion, according to Benefits and Work.
Why are PIP claimants getting extra money?
The issue stems from a High Court ruling in December 2017 that found the DWP had not correctly followed regulations for the points given for being able to go on journeys.
PIP is made up of two parts – a daily living rate for those who struggle with everyday tasks, and a mobility rate for those who need help going out or moving around.
The weekly rate for the mobility part of PIP is either £23.70 or £62.55, equivalent to £94.80 or £250.22 a month.
Claimants should have been awarded the standard mobility rate of PIP if their psychological distress meant they were unable to undertake any unfamiliar journey without having someone with them.
And they should have been given the enhanced rate if they could not go on any familiar journey without support.
But instead the DWP had been underscoring people for this part of the assessment, meaning some didn't qualify for the mobility rate of PIP at all.
Some qualified only for the daily living rate – and if they weren't eligible for that either, they received no PIP whatsoever.
The department is now reassessing claims and making adjustments that will mean extra cash and a big back payment for many who were turned down the first time around.
How many people are affected?
It is thought that 164,000 claimants are affected, including 143,000 who now qualify for PIP after being refused earlier, plus another 21,000 whose PIP would go up.
The DWP had been expected to face a bill of almost £3.7billion between 2017 to 2022, covering the new claims and all the backpay.
However, Benefits and Work believes less than 7,000 people will now end up qualifying for the extra cash.
So far, 900,000 people have been reassessed, according to DWP figures.
A DWP spokesperson said: "We already updated guidance for new PIP decisions to make sure people are receiving their full amount and are committed to making backdated payments for those eligible as soon as possible."