TDs and senators will be required to provide receipts for their expenses under new proposals from the body which oversees the day-to-day running of the Oireachtas.
At the launch of its first annual report, the Oireachtas Commission said that it had decided in principle to change the current system of unvouched expenses.
The annual report by the commission, which is made up principally of TDs and senators from the various parties and established last year, also showed that the cost of running Leinster House will reach more than €100 million this year.
Commission members warned, however, that the level of expenses for TDs and senators may increase as a result, with Oireachtas members claiming for costs they might normally pay out of their own pockets.
Currently members are entitled to a range of unvouched allowances, including mileage, overnight, secretarial and office allowances.
Last year TDs and senators received received more than €10 million in expenses. This included €3.42 million in mileage for TDs, €1.68 million for senators and €489,000 for committee travel.
TDs and senators received a further €8.2 million in other expenses, including office, telephone and overnight allowances.
In relation to most expenses, they are not required to provide receipts, and instead received fixed amounts tax free.
Yesterday, Dáil Ceann Comhairle Rory O'Hanlon said that while there had been isolated incidents of abuse, such as the use of free Dáil post facilities, there was was no evidence that this system was being abused.
Commission member Brendan Howlin of Labour said the introduction of a vouched expenses system was to introduce "transparency" to the payments rather than because of a suspicion the current system was being abused.
The commission is to work on a detailed set of proposals, some of which will need regulations and legislation.
It hopes the new arrangements will be in place following the next general and Seanad elections.
Commission member Joe O'Toole said the commission wanted to be "a watchdog rather than a bloodhound".
However, he warned that expenses could actually increase. "At the end of the day it will not be cheaper," he said, citing internal constituency travel as a possible new expense that is not paid for at present but might be introduced under a new system.
He cited a similar change in the British Houses of Parliament where costs actually rose when the vouched system came into force.
"Vouching is a huge issue, its sounds great and is from a transparency point of view, but we're not convinced it's a better value for money approach."
Last year the operation of the Houses of the Oireachtas cost €83 million, which will rise by more than €20 million to €104 million this year. The main cause of the rise is the introduction of parliamentary assistants for every TD.