There was very little surprise this week when it was confirmed that State-owned bank ACC had been one of the worst offenders in the DIRT scandal. Despite the bank's protestations to the Dail Committee of Public Accounts (PAC), it had been widely expected that its final bill would exceed its own £1.5 million (€1.9 million) estimate and, true enough, the bottom line of £17.9 million put the earlier "guesstimate" in the shade.

The only surprising element of the announcement was the bank's stumbling explanation of the difference in its earlier estimate and the final bill. Colm Darling, chief executive of ACCBank, essentially said the reason for the difference was that the Revenue had had longer to concentrate on unearthing the full scale of the problem.

The bank, when called upon to co-operate with the PAC inquiry, conducted its internal investigation and produced a figure which turns out to be a fraction of the final total. The bank, one would assume, would be most familiar with its own structures and processes and best able to speedily assess such a problem within its company. But it wasn't. Whatever the final bill for the foray outside the law on DIRT, the bank's actions in accounting for the scale of the problem do little to inspire confidence as it seeks to secure its future.