Sinn Fein is milking Westminster to claim £460,000 a year for its constituency offices in Northern Ireland — despite none of its MPs taking their seats.
And its TDs are breaking parliamentary rules in the Republic by paying activists out of cash claimed for travel expenses.
Sinn Fein said people voted for its abstentionist MPs and that it used the money to provide “first-class constituency services”.
Recently, the party announced four MPs who are also MLAs would stand down from the Assembly to concentrate on Westminster.
The move could prove lucrative. Sinn Fein would have lost more than £700,000 in future expenses had they not ordered its five MPs to quit Stormont.
A redrafting of expenses by the Report of the Independent Financial Review Panel will progressively reduce the £73,583 in office expenses MLAs now receive.
If an Assembly member was also an MP they were entitled to just half the office expenses a non double-jobbing MLA received.
But the amount of Office Cost Expenditure (OCE) payable to MLAs who are also MPs is limited to £27,594 per annum this financial year, £17,844 for 2013/14 and £8,655 for 2014/15, an Assembly spokesperson said.
When the four Sinn Fein MPs quitting the Assembly are replaced and Deputy First Minister Martin McGuinness steps down as an MP, the party will benefit from full OCE allowances.
Meanwhile, prominent front benchers in the Irish government have revealed that part of their expenses claims were diverted to pay additional staff.
Unspent travel expenses are supposed to be returned under rules introduced in 2010.
Yet in one case, Sinn Fein finance spokesman Pearse Doherty put €8,000 (£6,500) worth of unspent travel and accommodation expenses towards hiring part-time party workers.
Another frontbencher, foreign affairs spokesman Padraig MacLochlainn, also confirmed that he used unspent expenses in the same way. The revelation is likely to fuel calls for an inquiry into how the party uses taxpayer funds. Despite the admissions, Sinn Fein headquarters last night denied that its TDs were using unspent expenses in this way.