Good article that delves into UCI corruption among other things.
The non-payment of the UCI-required minimum salaries to riders is common among many teams. One source told me that he thinks every pro-continental team has at least some riders being underpaid in this way. One method teams employ is to create two separate contracts for a rider. One contract is the official one sent to the UCI which lists the normal minimum salary as the amount the rider will be paid. The second contract is the real albeit secret one, which specifies the lower salary amount that the rider will actually get. In some cases, the rider is paid the official UCI-contract amount, but then is quietly required to pay back part of this to the team according to the second real contract amount. In other cases the team pays the salary but then requires the rider to buy his own bike and/or other expensive equipment for the season, and then the team takes the bike to sell at the end of the season, leaving the rider with a pitifully small net gain. Other scenarios are teams that make the riders pay for all kinds of expenses themselves that are supposed to be paid by the team, so that in the end the rider is making far less than the required minimum salary.
http://cyclingfansanonymous.blogspot.com/2007/11/who-speaks-for-riders.html