FIANNA FAIL sources are apoplectic with fury at the disclosure of his private correspondence with the Revenue Commissioners.
While they darkly suspect persons with an agenda of having engineered the leak, carried in a Sunday newspaper, it is the substance of the material that will be of greatest concern to the public.
The nub of the correspondence is that the Revenue is claiming to be unaware of the Taoiseach's various dig-outs in 1993 and 1994.
It wrote to Mr Ahern in the wake of Bertie going on television in 2006 to claim there were no tax implications to his taking money in St Luke's, at the Four Seasons Hotel in Manchester, and at Beaumont House, all in the space of nine months.
Mr Ahern obtained a tax clearance cert in 2002 on the basis of having made a sworn statutory declaration that he was fully tax compliant.
While that might have been a matter of opinion, the binding opinion is that of the Revenue Commissioners themselves, as many have found to their cost. But the point would seem to be that the Revenue Commissioners do not consider that they were ever put in a position to adjudicate on the matter.
The Taoiseach is understood to be considering issuing a statement, as demanded by Labour leader Eamon Gilmore. His problem is that he told the people in a TV interview -- devised to appeal directly to the public -- that he had "broken no law".
He claimed to know the tax law, since he was an accountant. By Mr Ahern's formulae, the monies received in Ireland were "loans", while some £8,000 received from businessmen in Manchester was a "gift."
The Taoiseach said his two supposed dig-outs in Ireland -- the basis for explaining sums of IR£22,500 and IR£16,500 -- had been cleared with the authorities. He told the Dail on September 27, 2006: "I checked the matter with senior counsel and the tax authorities long ago." But the Revenue Commissioners say they have no record of this.
Des Peelo, former accountant to Charlie Haughey, wrote back on Mr Ahern's behalf, saying "the tax authorities" was intended to mean "authorities on tax", being his own advisers.
Mr Peelo has been retained by Mr Ahern only since 2005. Last night Fine Gael was demanding the Taoiseach state clearly the identity of those tax advisers who could offer such advice at the time of receipt.
The main opposition party is arguing that Mr Ahern's prepayment of a substantial amount of euro to the Revenue since Bertiegate broke, pending determination of the matter, is a clear indication that liabilities always arose -- and existed, uncleared, in 2002 when Mr Ahern made his statutory declaration to the actual tax authorities.
Labour leader Eamon Gilmore says the new revelations about the Revenue's lack of knowledge of dig-outs prior to the Taoiseach's TV confessional have now raised "extremely serious issues for Mr Ahern."
Both opposition parties contend that it now appears the Irish people, the Dail, the Revenue and the Standards Commission were all "seriously misled" by the Taoiseach on his payments.
Meanwhile Mr Ahern's patchwork quilt of explanation -- desperately darned to fill each fresh hole -- appears increasingly threadbare. Through the thin fabric can now be glimpsed the spectre of the taxman, scythe held high.