Jim Armitage: George Osborne's vow to raise £3.4bn from tax dodgers was cuckoo

Outlook If there's one thing you'll get accountants to agree with, it's that government pledges to recoup billions from tax avoiders are always massively overstated.

Yesterday, in the bowels of the official data on the public finances, the beancounters were proved correct, yet again.

The numbers show just how hollow was George Osborne's pledge to raise £3.45bn from his deal with the Swiss tax authorities to share the details of wealthy Brits sheltering their loot in private banks in the Alpine state. Under the agreement, Brits with accounts in the land of cuckoo clocks could either make a one-off payment to clear their outstanding UK taxes or have the Swiss authorities turn over your bank details to Her Majesty's Revenue and Customs.

So, how much of that £3.45bn has actually materialised in the Treasury coffers? £3bn? £2bn? £1bn? None of the above. In fact, only £800m has been recouped under the deal – less than a quarter of what the Chancellor promised. This could mean one of two things: either the accounts were not hiding tax dodges in the first place, or the money had been spirited away before the agreement came into force. I know which of those scenarios I'd bet on.

It's not just that Swiss deal that has been a disappointment. HMRC has, you could argue, failed dismally to capitalise on the juicy list of wealthy tax avoiders on the computer disk stolen by an employee at HSBC's Swiss private banking arm in 2008. A total of 800 Brits out of a list of 7,000 were said to be under investigation in 2011. How many have been prosecuted so far? One.

The fact is that recouping taxes evaded by our richest and best advised citizens is costly, time consuming and requiring of well-resourced tax experts. The average tax QC or partner is paid in the hundreds of thousands of pounds. The average taxman is paid in the dozens of thousands. For the best, only the lure of the revolving door into a big accountancy firm keeps their spirits up.

Although the HMRC has wrested an extra £1bn of budget to chase tax cheats in the past few years, the overall departmental wage bill is anticipated to fall from its £2.6bn levels in 2008/9 to £2.1bn this year, according to its last annual report. That's an average salary of just north of £32,000 and, almost to the penny, half of the average wage at PwC.

HMRC is an easy target to kick, just like the similarly pitifully-resourced Serious Fraud Office, but until we give these organisations the budget and legislation they need, we should perhaps applaud what small achievements they do make.