As always it takes an outsider to show up what's really happening in Ireland. 

The extraordinary details in a 40-page report by a US senate committee led by former presidential contender John McCain are devastating for our reputation.

Apple managed to avoid $25 million (€20m) a day last year in tax on the massive profits it earns from the iPhone and iPad. Over the last four years the use of three Irish-registered companies meant it was able to get around paying $44 billion in tax.

The report said we're a tax haven like Bermuda - a charge the government has denied. (I remember similar denials that Ireland was not like Iceland and Greece and look how that worked out!)

It is not simply a matter of the low rate of corporation tax at 12.5%. There is no doubt that the Irish tax system allows an incredible level of leeway to big companies to reduce their tax bills. Google is able to shunt billions of UK sales through Ireland by claiming clients were invoiced out of its Dublin office and cut its tax liability.

Apple is doing the same on a ramped up scale because of its sheer size.

We are not a traditional tax haven. These companies have substantial operations in Ireland. In Apple's case it has been in Cork since 1982 and employs 4,000 people. Google has its European headquarters in Dublin employing 2,500 workers.

Across any number of Caribbean tax havens a brass plaque is the most you're likely to find not a gleaming tower in the Dublin docklands.

But alongside offering a gateway to Europe for big multinational companies we have a hidden side. That is a generous tax system that has been in place for years and is successive government policy.

There are a number of methods to lower a tax bill here: transfer pricing, cost-sharing, mark-ups on products being sold from one side of a company to another. There is also the infamous "double Irish-Dutch sandwich" - an ingenious way of cutting tax bill by routing money through the Netherlands.

This has all been served to companies with the willing backing of policy and a creative legal and accounting industry. And it is all completely above board.

But has the country gone too far? It's all very well and good to say it benefits Ireland and that if it didn't happen here some other small country would do it but the mood globally is towards ensuring companies pay their fair share of taxes.

A startling figure is contained in the senate report. One of the three key Apple companies at the centre of the tax avoidance claims - ASI - does not pay corporation tax at the official rate of 12.5%. It doesn't pay it at the disputed arrangement between Apple and the government of 2%. In one year it had a tax rate of 0.05%. Another of the three companies, where $74bn in sales flowed through, hasn't paid any tax and has no country of residence.

So what can the government do to get rid of the image of being a tax haven? There is no doubt the complicated system that allows companies to lower tax needs to be looked at. And instead of being hostile to Europe on the tax base of companies, the government should co-operate.

Let's keep our corporation tax rate low. But let's ensure the companies here actually pay at that rate.