The MPs' expenses watchdog has been allowing politicians alleged to have broken rules to repay money and resolve issues in secret.
The Independent Parliamentary Standards Authority's (Ipsa) compliance officer Peter Davis has avoided naming individuals by carrying out detailed "assessments" of complaints - but denying they amount to "investigations".
The approach, revealed in response to a Freedom of Information request, emerged after Mr Davis was criticised for slipping out the fact that claims by three MPs had been referred to police last year.
The watchdog previously proposed conducting probes in secret to prevent "reputational damage" to MPs - but the idea was dropped by Ipsa after heavy criticism from the Commons Standards Committee and Committee for Standards in Public Life.
According to a breakdown of cases released by Mr Davis's office, which operates independently from Ipsa, he carried out 40 "assessments" of allegations against politicians in 2014-15.
But just one - relating to Tory Bob Blackman's mileage claims - was classified as a formal investigation and therefore disclosed publicly.
Among those listed as "closed prior to an investigation" was a case in June last year where an unnamed MP claimed for a taxi journey that was not allowable.
The compliance office concluded it had been a "legitimate error by a member of staff" and said it had been "repaid in full by the MP".
In another case, an allegation was made that an MP's staff had filed duplicate claims for a hotel. Mr Davis considered the matter closed after "the MP provided a valid explanation for why two separate hotels were claimed inadvertently for the same night and (...) repaid".
Other MPs were permitted to avoid publicity about using taxpayer-funded websites for party-political material by paying back website domain fees to Ipsa, or simply removing content from sites.
Many of the "assessments" appear to have gone into significant detail before being dropped.
A complaint about excessive toner ink and first class travel claims was dropped after "analysis of information provided by complainant and Ipsa showed no evidence of a scheme breach".
Another in October last year into whether an MP's claims for advertising had gone on "party political campaigning" was closed because "it was judged, on balance, that the adverts did not constitute campaign expenditure".
The FOI disclosure shows "allegations of a criminal nature" were made by Ipsa about the "staffing costs" of two unnamed MPs on February 4 and February 24. They were apparently referred to police the following month.
Former MP George Galloway was subject to complaints in January and March that his Commons staff were "engaged in non-parliamentary work during contracted hours".
Those allegations were both referred to Scotland Yard - but apparently not until March, and again without Mr Davis opening a formal investigation.
In August 2013 an MP's staff member alleged that some employees of a politician were engaged in non-parliamentary work during contracted hours.
This probe was later suspended due to "ongoing criminal proceedings related to the complainant". It is not clear whether it has been concluded.
The approach taken by Mr Davis means that Ipsa's regime is less transparent than that operated by the House of Commons.
Referrals to the police at the request of parliamentary standards commissioner Kathryn Hudson have been announced publicly.
She also publishes details of cases that are "rectified" with small repayments or apologies, and information about complaints that are not upheld.
Mr Davis, a former senior police officer, had not revealed the fact that MPs had been referred to the police before it was mentioned in three paragraphs on page 74 of his 77-page annual report last week.
In the report, he defended his approach to publicity, stressing that he would do as required and no more.
He said: "I am cognisant that publicity, especially in cases without foundation, carries an inherent risk of reputational damage."
He said the procedures governing his role set out the "information I am required to publish with respect to an investigation, and when this should take place". He said: "I will not deviate from this."
In evidence to the Standards Committee in October last year, Mr Davis indicated that he would like even less transparency.
He said: "I can see that the vast majority of cases can be dealt with quite effectively without the need for any publicity."