More than €583,000 was held in accounts linked to political parties last year, the Standards in Public Office Commission has found.
However, there is no requirement on parties to declare donations to these so called “accounting units”.
The commission says this makes it difficult to ascertain the source of the money.
It has now called for changes to legislation to ensure full transparency in this area.
Fine Gael has 41 “accounting units”, Fianna Fáil has 36, Labour 32, Sinn Féin 14, the Greens 13 and Solidarity-PBP 11.
The commission also published the declared donations to political parties last year which amounted to a total of €163,640.
Fine Gael received €65,324 in donations, the Socialist Party €39,518, Sinn Féin got €32,883, Labour €4,900, Social Democrats €5,000, the Greens received €6,500 and the AAA-PBP, now known as Solidarity-PBP, got €4,800 in donations.
Parties are required to declare donations exceeding €1,500.