Elliot Morley, David Chaytor, Jim Devine and Lord Hanningfield face charges
Lawyers for the three Labour MPs facing charges over their expense claims say their cases should be dealt with by Parliament rather than the police.
Elliot Morley, David Chaytor, Jim Devine - and the Conservative peer Lord Hanningfield - will be charged with false accounting under the Theft Act.
The MPs' lawyers believe they cannot be tried in court, claiming their cases are covered by Parliamentary privilege.
All four deny the allegations and have vowed to defend themselves "robustly".
The charges were announced by the Director of Public Prosecutions Keir Starmer on Friday following a nine-month police investigation.
The probe was triggered after details of all MPs' expenses claims were leaked to a national newspaper.
Another case remains under investigation but police said in a sixth case - that of Labour peer Lord Clarke - there was "insufficient evidence to provide a realistic prospect of a conviction".
The four men will not be arrested but will be sent a summons to turn up on 11 March at City of Westminster magistrates court, a short walk from the Houses of Parliament.
They face charges of false accounting under section 17 of the Theft Act 1968. If found guilty they face a maximum sentence of seven years' imprisonment.
In a joint statement, the three Labour MPs, who have been barred from standing as Labour candidates in the general election, said: "We totally refute any charges that we have committed an offence and we will defend our position robustly.
"We maintain that this is an issue that should be resolved by the parliamentary commissioner who is there to enforce any breach of the rules."
Keir Starmer said defence lawyers had raised parliamentary privilege
It is understood their lawyers might claim their expenses are covered by Parliamentary privilege, which traditionally protects MPs from being sued for what they say in the Commons.
Mr Starmer addressed the issue of Parliamentary privilege, saying: "Lawyers representing those who have been charged have raised with us the question of Parliamentary privilege.
"We have considered that question and concluded that the applicability and extent of any Parliamentary privilege claimed should be tested in court."
The Hansard Society, a leading political research and education charity, said any attempts to use parliamentary privilege in these circumstances would be a "deeply damaging" strategy.
Dr Ruth Fox, from the charity, said: "If it is a defence against almost any action that an MP takes in parliament, in any relationship with their work, then I think that is going to be deeply damaging for the public.
"They will see that it is putting MPs above the public, given them enhanced powers, making them essentially above the laws that they themselves make."
Paul Flynn, Labour MP for Newport West, thinks his fellow MPs would be misguided to try to use Parliamentary privilege.
"I'd appeal to my three colleagues to ignore the lawyers' argument and to go back to their political instincts, back to common sense, and see that no-one will respect any MP who uses this privilege to defend themselves," he said.
Former minister Elliot Morley, MP for Scunthorpe, faces charges relating to a total of £30,000 of mortgage claims which, it is alleged, were "in excess of that to which he was entitled" and covered a period when there was no mortgage on the property.
CPS CHARGES LAID
Elliot Morley - two charges over £30,000 of mortgage interest claims
David Chaytor - accused of dishonestly claiming £1,950 for IT services and also £18,000 in rent
Jim Devine - accused of claiming £3,240 for cleaning services and £5,505 for stationery
Lord Hanningfield - faces six charges of dishonestly submitting expense claims
David Chaytor, MP for Bury North, is accused of "dishonestly claiming" £1,950 for IT services and further sums of £12, 925 and £5,425 relating to rent on properties which he and his mother allegedly owned.
Livingston MP Jim Devine is accused of "dishonestly claiming" money for cleaning services and for stationery using false invoices. He told reporters he was "absolutely distraught" by the decision to press charges.
Paul White - the Conservative peer Lord Hanningfield and leader of Essex County Council - is accused of dishonestly submitting claims "for expenses to which he knew he was not entitled" - including overnight stays in London.
He stepped down as council leader on Friday and as a Tory frontbench spokesman.
He denies the charges and says he will "vigorously" defend himself against them adding: "All the claims I have ever made were made in good faith. I have never claimed more in expenses than I have spent in the course of my duties."
Another fall-out from the expenses scandal was announced on Thursday when 372 MPs were asked to pay back £1.1m as a result of an audit of their claims by Sir Thomas Legg.