It has taken almost an entire year to arrive at the point where the government will finally quantify, albeit in an estimate, the value of property loan assets on Irish banks' balance sheets.

Of course the value we are given on Wednesday in the Dáil won't be the market value of the assets, but at least we should learn what the "long term economic value" of the loans is and what the consequent capital requirements of the banking system might be.

Up to now the capital requirement has been the figure that dared not speak its name. A figure of €10bn in fresh capital for the banks cannot be ruled out.

However inadequate and incomplete the information provided by Brian Lenihan on Wednesday will be, we are almost a year on from the bank guarantee scheme and it's about time the Department of Finance shared its thinking with the rest of us.

Shareholders, taxpayers and bond-holders have a right to know what the government knows about the state of the banks' loan books. Unfortunately, the banks themselves should be disgorging the most compelling information about their loan books and their capital needs, but their credibility is shot with many market participants following their previously wonky bad debt forecasts. So its up to Brian Lenihan to fill us in.

One hopes he is as direct, honest and as frank as possible on Wednesday, because up to now advocates of Nama, nationalisation and the national recovery bank have been giving the public a somewhat selective account of what happens in financial crises and how the problem of impaired assets is dealt with.

When a country's banks lend recklessly, using money borrowed from other banks, the cost of cleaning up the mess is always enormous. There are no free or partially discounted lunches here, whether it's Nama, nationalisation or some kind of good bank/ bad bank construct.

The European Commission tells us just how fiscally expensive these crises are: if you take the 27 member states of the EU, for instance, governments recovered only 24% of the money they put in during their rescue measures. Admittedly, the Swedes, the Finns, the Japanese and Norwegians did a little better, recovering almost half of the money they invested to steady their financial systems.

But despite cheerleading on all sides, for nationalisation, Nama and the others, the cost of intervention is going to be huge in GDP terms. While it's possible to make rough estimates of the cost of Nama and even the national recovery bank solution, nationalisation comes with an unquantifiable cost, even its chief adherents admit.

Assessing the final cost of the asset relief scheme is all but impossible, and that is the point. The assets underpinning the loans are a contingent liability and at some point they have to be dealt with, even in the messy fashion provided for in an asset relief arrangement. But just how expensive could it get?

Well, when one considers that the cost of Ireland's bank rescue, as a percentage of GDP, will rank alongside those of Chile, Indonesia and Turkey, one gets a sense of the size of the mess we're in.

What is clear is that clean-up costs may vary, but it's going to be a messy job however it's done.