A new examination of 214 UK addresses given by holders of existing non-resident accounts found a "strong possibility" that 58, or 27 per cent, were bogus.
The examination formed part of an audit of the non-resident accounts in 22 financial institutions which found that non-resident declarations were missing in only 1.5 per cent of cases.
A reportable "deficiency", however, was found in more than a quarter of all forms. A reportable deficiency is a prima facie reason to declare a form invalid and could render the underlying account liable to DIRT.
The audit by Ms Aileen Barry, partner with Arthur Andersen in the UK, on behalf of the Comptroller and Auditor General, found that overall, 18 per cent of non-resident accounts sampled had factors indicative of a risk that the account holder was really resident in the State.
Factors indicating a risk include where mail is held at the branch for the depositor, where depositors use a "care of" address in the State, where the "care of" address is the bank branch itself, or where an address in this State is given.
A sample of 214 UK addresses given by account holders was examined for evidence of the account-holder having been resident at the address in the period from 1986 to date.
The number of addresses classified as valid was 156, or 73 per cent. As for the other 58 addresses, Ms Barry concluded there was "a strong possibility" that the account holder's non-residency status might not be genuine.
Companies subject to corporation tax, pension funds and charities are exempt from DIRT.
An examination of accounts in these categories found that in 9 per cent of cases, the declaration forms were not in existence.
Among Ms Barry's suggestions was that the institutions might appoint an officer responsible for compliance and implementation of a programme of training for staff. She also suggested the institutions might be offered the opportunity of appointing, at their own cost, a Revenue-approved independent auditor who would audit compliance, perhaps on a cyclical basis.
There are a little more than 300,000 non-resident accounts held in the banking network in the State, according to the comptroller's report.
AIB held the highest number with nearly 90,000 accounts, followed by Bank of Ireland which held 74,888. The Border counties held a little over a fifth of non-resident accounts with the average Border branch holding around £3.7 million.
This is higher than in Dublin where the average total in each branch was £2.5 million.
Dublin held 27 per cent of total non-resident accounts, the west 22 per cent and the rest of the State 29 per cent.
The 40 urban centres in the State held 48 per cent of the value of non-resident accounts.
Dublin held 27 per cent of the non-resident accounts in the State, and branches in Dublin 2 held £386 million, more than three times the amount held in any other area in Dublin. Apart from Dublin 1 (£114.2 million) and Dublin 4 (£60.9 million), the amounts held in branches in the rest of Dublin were less than £40 million.