Negotiations between National Irish Bank and the Revenue Commissioners could lead to it making a final DIRT settlement this month.

The bank has made a provision of £1 million (€1.26 million) for potential DIRT liability. This is based on its own estimate of an underlying liability of £412,000 in unpaid DIRT.

The Revenue Commissioners is due to report on November 1st to the Dail Committee of Public Accounts with details of all tax assessments raised against 37 financial institutions.

These audits are continuing and the Revenue is in final negotiations with these institutions with more settlements expected in the coming weeks.

NIB, which was severely criticised in the PAC report on the DIRT inquiry, is expected to pay the largest amount. The Australian-owned bank is being separately investigated by the Tanaiste's Department over its role in selling an unauthorised offshore investment scheme to its customers.

The Revenue Commissioners has already secured payments from some of these customers for taxes which were evaded through the scheme while negotiations with others are ongoing. On Tuesday, AIB disclosed it had made the biggest tax settlement in the history of the State, paying £90 million to cover its DIRT arrears and interest and penalties applied by the Revenue Commissioners. AIB is the sixth institution to settle its DIRT arrears bringing the total payments so far to £157 million.

AIB shares closed six cents higher at €11.69 in Dublin yesterday with the stock expected to make further progress now that the DIRT issue has been dealt with. The scale of the settlement was also lower than most observers had expected.

The payment will not have any material impact on AIB Bank and represents just five weeks' profits. So far AIB, Bank of Ireland, ACC Bank, Ulster Bank and Irish Life & Permanent have settled their DIRT liabilities after lengthy audits. The payments have been made to cover all group subsidiaries which were independently audited by the Revenue.

When these subsidiaries are taken into account 24 institutions have yet to settle with the Revenue.

Many of these are companies based at Dublin's International Financial Services Centre and are unlikely to have substantial liabilities. Others include First Active, Irish Nationwide Building Society, An Post, ICC Bank and TSB Bank.