The report into claims made in a BBC NI Spotlight programme has been complete for more than seven months.
Publication has been delayed by a legal challenge from Iris Robinson's solicitor.
A reference to the legal challenge is contained in an annual report from the Assembly's standards watchdog.
The Spotlight programme, broadcast in January 2010, detailed how Mrs Robinson had obtained thousands of pounds from property developers to help her teenage lover to set up a business.
Standards Commissioner Douglas Bain investigated the allegations, but his report has not yet been published.
"My investigation into the referral relating to the allegations made in the BBC Spotlight programme broadcast in January 2010 was completed in November 2013," he said.
"However, submission of my report to the committee has been delayed by a legal challenge to its contents by a person referred to in the report."
Iris Robinson's solicitor, John McBurney, told the BBC he had concerns about the impact upon his client of the production of a range of documentation included with the draft report.
Those concerns relate to the relevancy of the material to the inquiry, Iris Robinson's privacy and the impact publication might have on her health and recovery.
A legal challenge has delayed the publication of an official report into allegations about the conduct of First Minister Peter Robinson and his wife.