The file from the police investigation into whether people were nominated for honours in return for money has been handed over to prosecutors.
Assistant Commissioner John Yates has been heading up the inquiry
The year-long probe had widened in recent months to look into any attempt to pervert the course of justice.
Scotland Yard said that 136 people had been interviewed. They include Tony Blair and some of his closest aides.
The Crown Prosecution Service will now decide whether anyone should be charged. All involved deny wrongdoing.
A Scotland Yard spokesman said that what they consider to be their main file on the investigation was "a 216 page report with supportive material".
He said there had been extensive consultation with the CPS during the inquiry, and this was the 12th police submission - in total they have handed over 6,300 documents.
He said it was now for the CPS to decide whether any charges should be brought.
The police inquiry began after it emerged that secret loans had been made to Labour before the 2005 general election, and that some lenders had subsequently been nominated for peerages. The probe was widened to include the other main parties.
Four people have been questioned under caution during the course of the inquiry, including Tony Blair's chief fundraiser Lord Levy and Number 10 aide Ruth Turner.
The first man arrested, head teacher Des Smith, has been told he will not face any charges. The others remain on police bail.
There has only ever been one prosecution involving the law at the centre of the inquiry - the 1925 Honours (Prevention of Abuses) Act - so it could take some time to decide whether to press ahead with a prosecution.
That decision will be made by Carmen Dowd, the head of the CPS's special crime division.
In a statement, the CPS said it had received the file, adding: "It will now be reviewed in accordance with the code for crown prosecutors to determine whether any individuals should be charged with any offences."
It added that the police would be told of the decision "in due course", and it would be made public, after the parties concerned had been told. Director of Public Prosecutions Ken McDonald has said he will stand back from any decision, because he is a former colleague of Cherie Blair.
The Attorney General, Lord Goldsmith, has resisted calls for him to stand aside from the decision on whether to have any prosecution because he is a close ally of Mr Blair.
He says his "constitutional responsibilities" do not allow him to do so, but has said he will make sure there are procedures in place to give confidence that the decision is taken impartially and objectively.
Scottish National Party MP Angus MacNeil, whose complaint initiated the investigation, said: "When I lodged the complaint, it was said that the police would turn a blind eye, but what we have had is a meticulous investigation."