The Dáil's Public Accounts Committee (PAC) has called on Revenue to commission an independent investigation into the self-employment status of couriers.
Committee Chair, Brian Stanley TD, said that it was clear that "if and when we need you employment" had become a problem.
In a report published this afternoon, the committee also called on Revenue to conduct a minimum of 4,000 site visits across all employment sectors from next year onwards, to tackle "bogus self-employment".
This followed a Revenue investigation in 2019, which found that 400 construction workers were incorrectly classified as self-employed, at a cost of at least €166 million to the state over three years.
PAC's report was compiled following an examination of Revenue's appropriation accounts for 2019.
"There has been a significant move in terms of casualisation, right across a range of sectors, not just in construction and courier" the Sinn Féin TD told journalists at the virtual launch of PAC's report.
While there are some couriers who own their own vehicles and are correctly classified as self-employed, there are others who should not be treated as such, he explained.
"The default position is that all couriers, everyone in the courier sector, is treated as self-employed unless the employer decides that they want to have them as an employee" Deputy Stanley said.
In the report, PAC members expressed concern that the exchequer had lost income due to couriers being treated as "self employed for tax purposes" and that couriers themselves may have lost out on benefits.
Social Democrats co-leader Catherine Murphy said that bogus self-employment also facilitated precarious working hours.
"It may well be that there's insufficient hours to sustain people" and there's a "lack of entitlements when it comes to PRSI and social welfare entitlements in the event of people becoming sick or indeed when they reach pension age", she explained.
Members were also mindful that the pandemic brought with it a significant increase in online shopping and deliveries.
"Anecdotally, an awful lot of stuff has been delivered online and indeed a lot of people took up temporary work during the pandemic as couriers.. and typically driving a van belonging to a firm or company", Deputy Stanley said.
PAC asked that Revenue commission an independent investigation to establish "the magnitude of revenue lost to the State as a result of this practice" and the cost to workers themselves.
Separately, the committee noted that Revenue visited 1,673 construction sites in 2019 and found that 400 construction workers, out of a total of 6,650, were wrongly classified as self-employed.
They have since been reclassified and the State recouped €166 million.
PAC recommended that a minimum of 4,000 site inspections be carried out across all sectors from 2022 onwards.
The report also raises issues separate to the 2019 appropriation accounts.
In 2020, Revenue themselves acknowledged that errors were made in the operation of the Temporary Wage Subsidy Scheme.
From 26 March to 3 May of that year, employers were paid the maximum entitlement of €410 for each employee, resulting in significant costs to the exchequer and a requirement to recoup money.
PAC asked Revenue to ensure that lessons are learned ahead of the rollout of any other future schemes.