People who claim Universal Credit could be in line for an increase of up to £405 a month from October.
Those who are eligible will automatically see their payments increase by £120, £285 or £405 next month.
The rise is designed to bridge the gap between the old benefits and Universal Credit, Birmingham Live reports, and applies to those who missed out during the switch over.
The payment drop affected those who switched to Universal Credit from Income Support, Jobseeker's Allowance (JSA), Employment and Support Allowance (ESA), Housing Benefit or Pension Credit, if they were also receiving a top-up allowance called Severe Disability Premium (SDP).
When moved from those 'legacy benefits' on to Universal Credit they discovered find the amount they received was far lower.
Campaigners fought to get back the lost money and the DWP agreed to give "transitional payments" in an effort to make up the difference.
These came in the form of extra monthly amounts of £120, £285 or £405 awarded to people, depending whether they were claiming as a single person or a couple, and whether or not they were expected to be looking for work.
Justin Tomlinson, a Minister of State at the Department for Work and Pensions, has now confirmed these transitional sums will be added to a person's regular Universal Credit payout, starting from October 8.
He said the DWP had already paid out over £50 million to around 15,000 people who lost out when switching to Universal Credit.
And the extra money is now to be built into the regular Universal Credit payout, rather than claimants hoping to get it paid manually in separate payouts by DWP staff.
Mr Tomlinson said: "On July 22 2019, we laid legislation to provide additional financial support for former SDP recipients who had moved to Universal Credit on account of a change of circumstances.
"As at January 17 2020, we had already paid over 15,000 people, totalling more than £51.5 million.
"The UC (Managed Migration Pilot and Miscellaneous Amendments) Regulations 2019 provide for the conversion of these transitional payments into transitional elements.
"This means that payments will be made through the UC system rather than manually, and all transitional protection will be subject to the same rules.
"I will be signing a Determination setting the conversion day to 8 October 2020. This is when the UC system will have capacity to convert SDP transitional payments to transitional element."
