Of the 311 investigations commenced by the Department of Social Protection's Employment Status Unit, over one third have related to the media and journalism sectors.
The finding is contained on the Comptroller & Auditor General's annual report.
The ESIU was established in 2019 with the aim of detecting and investigating misclassification of employment status.
To date, the office has focused mainly on the media and construction industries, but it has identified misclassifications in a range of industries.
According to the C&AG report, 110 cases have related to media and journalism which has already resulted in €452,000 being charged to employers in arrears in that sector.
That is more than half of the €811,000 charged in arrears so far to employers since the office was established in mid-2019.
167 of the more than 300 investigations commenced had been completed by August of this year, the report shows.
That resulted in the reclassification of 93 workers for PRSI purposes.
Misclassification of employment status mainly arises where a worker is classified as self-employed but has the characteristics of being an employee.
It can result in a loss of PRSI contribution income for the Social Insurance Fund (SIF), but may also result in misclassified workers being deprived of access to social insurance benefits in the long term.
"There is no reliable estimate of the level of misclassification of employment status in Ireland," the report concludes, noting that the office has been in existence only for a few years.