The court of appeal has quashed the convictions of two former Anglo Irish Bank officials Tiarnan O'Mahoney and Bernard Daly.
They were jailed last year for conspiracy to falsify bank records and defraud the revenue commissioners.
No retrial has been ordered for Mr Daly and he has been released from custody.
Mr O'Mahoney has been released on bail until 14 April when the court will hear submissions later on whether or not he should be retried.
The court of appeal ruled that inadmissible evidence was allowed in the trial and the prosecution was out of time on other charges.
It also said the trial judge erred in his direction to the jury on other issues.
Mr O'Mahoney, 56, of Glen Pines, Enniskerry, Co Wicklow and Mr Daly, 67, of Collins Avenue, Whitehall in Dublin, had denied knowingly furnishing false information and conspiring to defraud the Revenue as well as conspiring to have accounts deleted from the bank's internal system.
Having been found guilty by a jury at Dublin Circuit Criminal Court, Judge Patrick McCartan jailed Mr O'Mahoney for three years and Mr Daly for two years on 31 July 2015.