The National Audit Office investigation into the Compact has been delayed by five months and may not be made public.
The spending watchdog’s investigation was announced last year as part of a series of measures that Nick Hurd, the Minister for Civil Society, said would provide an "unprecedented level of scrutiny of the Compact".
The NAO will analyse implementation of the Compact, the public and voluntary sector fair-play agreement, across government.
Fieldwork was due to start in April and the report was due in July.
But an NAO spokesman told Third Sector the report was now not expected until Christmas.
He would not say why it had been delayed. "We do not give blow-by-blow accounts," he said.
The spokesman said the NAO investigation was conducted at the request of Hurd and a decision had yet to be made on whether to lay it before parliament in the usual way or send it to the Office for Civil Society – in which case the department will decide whether to make the findings public.
No one from the OCS was available for comment.
Simon Blake, chair of Compact Voice, which represents the voluntary sector on the Compact, said he was concerned about the delay because the report would lead to better practice.