Two teaching contracts, alarm bells ringing, definitely somebody is at it. Similarly, a western friend of mine here on mainland, bought a new apartment. After a lengthy time, he had to apply for a housebook, not cheap, as it includes buyer's purchase tax. At that time, the property developer's wife wanted to do a new contract, reducing the flat's area from 103 square meters to 98! The foreigner's wife refused, because were the apartment ever to be sold on, her husband would get less for it, on account of its reduced area. She reckoned that the property developer wanted to cheat the local government out of tax, coz he'd have to pay tax too! Of course, by means of the area reduction, said foreigner could have cheated tax too. Being honest, he refused to do a new contract.
More about tax evasion on mainland. Said foreigner was teaching in a provincial capital at a public college. Ten days or so before he was due to finish his teaching there, his Chinese wife went to the railroad station to buy tickets for their departure for a holiday in Xiamen. The college FAO asked his wife to ask other travelers for their used tickets at the railroad station, and give him the ones that had been used for long journeys, as they were more 'valuable'. When she asked him why, he told her that they were needed by the college accountant for tax purposes!