Nobody, not even the Receiver of Revenue, knows how much the State loses every year in the form of lost revenue.
Various commissions of enquiry have commented on this issue and the amount ranges from R5 billion to as much as R22 billion per year.
Whatever the amount, it's huge and the government is anxious to get its hands on at least some of this money.
Now, I'm not normally in favour of any steps to increase government revenue, but in this case the government has my full backing.
The simple reason is that if more revenue can be collected from this untapped source, the greater the likelihood of personal taxes coming down in years ahead.
Individual taxpayers now contribute the bulk of government revenue and middle-class South Africans are in danger of collapsing under the sheer weight of fiscal drag.
Recently it was reported in Parliament that this country has only about 4 million registered individual taxpayers, less than 10 percent of the population.
In the old days tax-dodging was justified on the basis that people did not want to be seen supporting the apartheid system. Nowadays, most probably the same dodgers, justify their actions by saying something to the effect that the government is corrupt anyway, so why should they pay taxes? The new tax dodgers, I'm told by sources at Revenue, apparently justify their actions by saying that they have not been paying taxes for so long, so why should they start paying now?
Whatever the reason, I don't envy the task of the newly reconstituted SA Revenue Services to change the culture of non-payment.
Salaried taxpayers are somewhat bemused by all this talk of tax dodging as most have no choice in this matter. Tax is deducted in terms of either standard income tax on employees (Site) or pay-as-you-earn (Paye) and that's the end of it.
However, it's usually people who own their businesses who try and evade paying tax or try and overstate their expenses.
By introducing the Site system, amongst other things, the Department of Inland Revenue has freed a great number of staff to concentrate on large scale evasion of income tax.
In recent years newly qualified chartered accountants have also been used with great effect to ensnare taxpayers who cheat.
Cheating normally consists of under-declaring (or not declaring) income or overstating expenses. Both have the same effect: they rob the State of revenue which has to be sought from other more honest taxpayers.
Spot checks on self-employed people are one way of checking (and catching out such offenders), but this can be an arduous task.
More successful are the lesser-known techniques which are employed by the Revenue official to trap cheaters. Driving around in a very expensive and flashy car might not only make you a target for hijacking it could also alert the Receiver about possible income tax evasion.
On my Radio 702 show some time ago a senior official from the the Revenue Service admitted that his officials drive around town taking down the registration numbers of expensive cars.
The number is traced back to the owners who are then subjected to a spot test. If their declared income does not match their lifestyle, their financial affairs will be investigated thoroughly. The same method is used when any display of wealth could attract the eyes of the taxman.
But, perhaps the best sources of information are jealous friends or family or jilted ex-lovers. Obviously, there is no revenge so sweet as to inform the Receiver of Revenue of someone's tax affairs, especially if that someone frequently boasted about how little income tax he or she pays.
The same goes for friends, family and neighbours who might not like the boasting by someone about how he or she manages to cheat the Receiver of Revenue. Even more disconcerting if you are cheating on the taxman, the person who successfully blows the whistle on you will be rewarded up to 10 percent, fully taxable off course, of any unpaid taxes found by the taxman.
However, one cannot make a sweeping statement that someone is cheating, it needs to be a very specific allegation with enough proof to justify the accusation.