Business minister Kevin Hollinrake said those affected had suffered “for too long” and so should be able to settle their claims “swiftly if they wish”.
The offer will be optional, the Government said, with those affected able to continue with the current compensation process if they choose.
The Horizon scandal – which has been described as the most widespread miscarriage of justice in UK history – saw more than 700 Post Office branch managers handed criminal convictions after faulty Fujitsu accounting software made it appear as though money was missing.
We hope that the change that I am announcing today will provide more reassurance and quicker compensation to those postmasters who prefer this option over going through the full assessment process
Kevin Hollinrake, business minister
The Government said 86 convictions have been overturned and £21 million has been paid in compensation.
Postmasters who have already received initial compensation payments or have reached a settlement with the Post Office of less than the £600,000 will be paid the difference, the Government said.
Making a statement in the Commons, Mr Hollinrake said: “The Government has decided that postmasters who have their convictions on the basis of Horizon evidence overturned should have the opportunity up front to accept an offer of a fixed sum in full and final settlement of their claim.
“The sum will be £600,000. It is not up to £600,000, it is £600,000. There will be no requirement for evidence to support the claim other than being able to demonstrate that the individual has an overturned conviction.”
He said the figure was arrived at by looking at existing claims that have been processed and applying a “generous uplift to that”.
He said: “This payment will be made net of any sums already received, such as interim payments and partial settlements to settle a claim fully.
“Any postmaster who does not want to accept this offer can of course continue with the existing process. It will therefore be completely optional to accept the offer.”
He added: “We hope that the change that I am announcing today will provide more reassurance and quicker compensation to those postmasters who prefer this option over going through the full assessment process.”
The minister acknowledged “some details will need to be worked through”, including how long the upfront offer remains open. But he said the Government wants to make sure it “gets this right” and does not want to delay informing postmasters that there would be an “optional, quick and straightforward route to settlement”.
The Government said it would continue to fund the legal costs of the postmasters to ensure they receive independent advice prior to making a decision.
Mr Hollinrake told the Commons: “Postmasters who have been wrongfully convicted have some of the most severe circumstances having lost clean records, and in some cases their liberty and suffered significant financial losses and an overwhelming impact on their lives.
“The Government recognises that these postmasters have suffered gravely in relation to the Horizon scandal, and for too long. So should be able to settle their claims swiftly if they wish.”
In isolation £600,000 may sound like a lot of money, and it is. But in many cases it is nowhere near enough to represent what has been lost over the last two decades
Neil Hudgell, solicitor
Solicitor Neil Hudgell, of Hudgell Solicitors, who represents 70 former subpostmasters who are seeking compensation from the Post Office after having convictions relating to the scandal overturned, said in many cases the offer is “nowhere near enough”.
He said: “We welcome any announcement that is in our clients’ best interests.
“Having spent many months negotiating with the Post Office and the Government as to what would represent fair and full compensation for former subpostmasters who have had convictions overturned, we are somewhat surprised by this sudden announcement.
“I expect the reaction of many of our clients will be that this move is another example of the Post Office trying to control the narrative here.
“The Government has said these offers are optional, but my fear is that, due to the delays we have already faced, and the particular circumstances many subpostmasters face, some may feel pressured to accept this offer even though their claims are worth much more.
“In isolation £600,000 may sound like a lot of money, and it is. But in many cases it is nowhere near enough to represent what has been lost over the last two decades.”
This will be an entirely voluntary choice and so claimants should obtain specific advice from their independent legal and professional representatives in considering whether it is suitable
Nick Read, Post Office chief executive
Starting in the late 1990s, the Post Office began installing Horizon accounting software, but faults in the software led to shortfalls in branches’ accounts.
The Post Office demanded subpostmasters cover the shortfalls, and in many cases wrongfully prosecuted them between 1999 and 2015 for false accounting or theft.
An independent inquiry is ongoing.
The Overturned Convictions process, Horizon Shortfall Scheme and Group Litigation Order have in total paid more than £120 million to 2,600 individuals affected by the Horizon scandal, the Government said.
The Post Office said it welcomed the announcement but also said the offer is not expected to be appropriate in every case.
Post Office chief executive Nick Read said: “Post Office is making good progress to pay compensation to those affected as quickly as possible and therefore welcomes the news that Government has found a way to provide the option of concluding settlements through their upfront offer.
“This will be an entirely voluntary choice and so claimants should obtain specific advice from their independent legal and professional representatives in considering whether it is suitable in their individual case.”