Taxpayers could face a record £10million bill to cover the costs of departing MPs at the general election, the Mail can reveal.

Official estimates suggest it costs an average of £116,000 per MP when they decide to stand down.

The sum covers staff redundancy, the cost of closing down an office, secure disposal of documents and winding-up payments to MPs - akin to redundancy.

The severance payment was doubled last year to more than £19,000, with MPs to be paid for four months instead of two while they close their office and manage the departure of staff.

All MPs are eligible for the payment if they stand down at a general election.

Some 63 Tories have already said they do not plan on defending their seats in an election that has yet to be given a date.

In 1997, in the run up to Tony Blair's New Labour landslide, a record 72 stood down. Party insiders believe the final figure this time round could top 100.

This week two senior Tories who are standing down at the election - James Heappey and Robert Halfon - quit their ministerial posts.

They followed the recent announcements of former prime minister Theresa May, who will leave Parliament after 27 years on the green benches, and former cabinet minister and party chairman Sir Brandon Lewis.

Others who will not compete include the chairman of the influential 1922 committee of backbenchers Sir Graham Brady, ex-sports minister Tracey Crouch, former home secretaries Sajid Javid and Dominic Raab and previous defence secretary Ben Wallace.

The total cost to taxpayers for managing the cost of departing MPs was revealed in a meeting of the Speaker's Committee for the Independent Parliamentary Standards Authority (IPSA).

According to the minutes, Labour frontbencher Lucy Powell said that IPSA had 'estimated costs of managing the departure of one MP are £116,000 when you take all those things into account'.

'The House of Commons Library has already produced a tracking spreadsheet of those who have said they are standing down,' she said.

'Notwithstanding any changes through a general election, that list is already at 100, so that is £10million to start off with.'

Ipsa chair Richard Lloyd replied: 'Many MPs having already declared that they are standing down has been helpful to us in our planning.

'We have done numerous winding up sessions with MPs already, helping them to prepare for winding up their offices and the like, so we are well ahead and better prepared than IPSA has ever been for a general election.

'It is helpful that we have had those declarations early. We will inevitably have to do a supplementary estimate, though, because that won't be the full size of it, one assumes.'

Around 20 Labour MPs have also announced they will quit at the election.