here's what can happen
A Long time ago in a land far away I played with a fellow at a certain gov't affiliated watering hole on a regular basis. We were a four piece band playing for union scale plus, i.e we did a five way split, two for the leader and one for each of the other three guys.
The establishment paid the leader by cheque, and he brought enough cash to pay the three sidemen. So the folks at revenue Canada audited the gov't institution and duly noted cheques made out to our leader going back a few years. Being the curious types they are,they decided to audit his taxes and, guess what? no mention of said income: he was ordered to pay delinquent taxes and interest, and fines totalling $5000.00; worst of it was he paid our share too, on money he didn't get!