The investigation into Ms Berejiklian began after the Independent Commission Against Corruption launched inquiries into disgraced former Liberal Wagga Wagga MP, Daryl Maguire.
The watchdog is probing whether Mr Maguire used his role as an MP to gain a financial benefit, and whether Ms Berejiklian breached the public trust during their five-year secret personal relationship.
The ICAC said the final report was due by the end of next month, after revealing in January that it would not be released before the March election.
“The commission remains conscious of its obligation to furnish the report as soon as possible after it has concluded its involvement in the matter, and continues to anticipate the report will be ready to be furnished during this quarter,” a spokesperson told AAP.
The corruption watchdog said the report concerned complex matters of law and fact, two public inquiries that proceeded over 30 days, more than 2800 pages of transcript, 516 exhibits comprising about 10,600 pages, and 957 pages of submissions.
The report, dubbed Operation Keppel, is set to be published nearly 18 months after Ms Berejiklian resigned as premier in October 2021, and more than two and a half years after she first gave evidence about her secret romance with Mr Maguire.
The investigation of the former premier hinges on whether concealing the relationship breached the public trust, whether she improperly handled projects pursued by Mr Maguire, and if she engaged in conduct “liable to allow or encourage corruption” by him.
Ms Berejiklian has denied any wrongdoing, and cited concerns about likely lengthy delays as a reason for her resignation.