It's safe to say €137.5bn is a very large sum of money. It’s an amount you’d think it would be difficult to mislay.
Nevertheless, last week’s report from the European Commission on the Vat gap suggests exactly that.
The Vat gap is the overall difference between the expected Vat and the amount actually collected by revenue authorities across Europe, including our own Revenue Commissioners, and its estimated total for 2017 is €137.5bn.
That’s a shortfall of about 11%.
Value Added Tax is a tax paid mostly by individual consumers rather than by businesses.
The "value-added" in the title doesn't refer to the increase in price which results from applying Vat, but to the notion that as they make their way to the final consumer, various things happen to goods and services which add value.
While most of us can see how processing or refining a raw material can actually add value, the taxman considers that when a wholesaler sells to a retailer, that is also a value-added event.
For consumers, the Vat is usually bundled into the price of the item and the amount it adds to the price is largely invisible.
As the EU report highlights, the current Vat system is not foolproof and that is partly because it is growing old. Fraud and evasion have always contributed to a shortfall in Vat receipts, but the emergence of the high-tech economy has also blunted its collection capacity.
For example, streaming services are replacing physical CDs and DVDs, online subscriptions are replacing books and magazines, and thus different Vat rules and rates can start to apply.
Cross-border fraud is also a particular bugbear for tax authorities.
Many businesses are able to reclaim any Vat that they pay on goods or services which are provided to them, but that only works if the businesses they have bought from are playing fair, and have properly paid over the Vat they charged in the first place.
This becomes more difficult to enforce with cross-border sales, so much so that there are now separate and time consuming checks in place when a foreign business wants to register for Irish Vat.
It is, of course, possible to question the EU report’s findings, based as they are on estimates of sales, consumption and demand.
These types of estimate can be fraught with problems, particularly where results from 28 individual countries are being compiled.
With an estimated shortfall in Vat collection of 13%, Ireland doesn’t fare particularly well in the EU Vat gap findings, but country-by-country comparisons are a little suspect.
Not too much should be read into how much better or worse some countries are at collecting Vat.
Nevertheless, Vat collection is big business and a significant contributor to exchequer returns.
Since January of this year, Vat has yielded almost €10bn making it the second most important tax in terms of the overall amount collected – only the yield from income tax is larger.
Even a small improvement in Vat collection would make an appreciable difference to the national finances.
As with so many other things, Brexit creates its own Vat problems. Importing items from outside the EU triggers the collection of a Vat charge, so imports from the UK coming into Ireland will be subject to Vat once the British finally do leave the EU.
While the Brexit Omnibus Act - which sets out the position on many cross-border arrangements in the event of a no-deal outcome - does provide some help for Irish importers in paying that Vat, this Vat charge provides another reason for stringent border checks and controls between Britain and the rest of the EU.
Given the existing size of the Vat gap, it is unlikely that any EU member country will want to risk having any further slippage in Vat collection.
Dr Brian Keegan is director of public policy at Chartered Accountants Ireland