A reform of political expenses, which allowed former taoisigh to claim so-called "turning up" allowances at the Dáil despite having state cars, has benefitted only Bertie Ahern, it has emerged.

The amended legislation, introduced by former finance minister Charlie McCreevy in 1998, created a Dáil expenses system that was less transparent for the public but far easier for TDs and senators to use. It included a clause allowing office holders – who get to keep their state car even after stepping down – to claim for a generous €61.50 daily allowance just for going to work.

Ironically, the only person to have benefitted from the amendment has been former taoiseach Bertie Ahern, who in 2008 claimed €3,630 tax-free just for turning up at the Dáil. Despite having round-the-clock access to a garda driver and a ministerial Merc, Ahern claimed the allowance for the period between May and October 2008.

The former taoiseach, who has several other sources of income apart from his TD's salary, has not claimed since then but will be able to backdate as long as he claims before the end of July.

It has since emerged that the amending legislation was introduced by McCreevy and approved by Ahern, the then taoiseach, at a cabinet meeting.

It states that all references shall in future be "construed as including a former taoiseach, or any other former office-holder, who is not currently an office-holder and who has the use of a state car while continuing to serve as a member".

According to the most recent figures, Ahern has claimed €65,175 in expenses since stepping down as taoiseach, primarily for his constituency office and phone bill.

If he chooses to claim the rest of his turning-up money, the bill to the taxpayer is likely to be at least €8,500 a year.