Short answer: a second income is not automatically a crime in China, but it can become illegal employment if you work outside the scope of your work permit. Under the Exit and Entry Administration Law, your right to work is tied to a work permit and a work-type residence permit issued for a specific employer and position — so a second job with another employer is only safe once your permit covers it.
What the law actually says
Article 41 of the Exit and Entry Administration Law provides that foreigners working in China must obtain a work permit and a work-type residence permit, and that no entity or individual may employ a foreigner who does not have them.
Article 43 then defines illegal employment. It covers working without the required work permit and work-type residence permit, and — the point most people miss — working beyond the scope permitted by the work permit. Foreign students who exceed the jobs or hours allowed under the work-study rules fall into the same category.
The consequences are administrative rather than criminal: a fine of RMB 5,000 to 20,000, and in serious cases five to 15 days of detention plus the same fine (Article 80). The employer can be fined RMB 10,000 for each illegally employed foreigner, up to RMB 100,000. Illegal employment is also one of the grounds for being sent out of China under Article 62 — and a person removed on that basis may be barred from re-entering for one to five years.
What this means in practice
Your work permit is not a general licence to work anywhere in China. It is issued for a named employer and a named position. If you take weekend consulting work for a different company, or a second salaried role, that work sits outside your permit. In practice the fix is procedural rather than secret: the second employer applies for its own work permit for you, or your existing permit is changed or transferred, and your residence permit is updated to match. Doing that paperwork in advance is what separates a lawful second job from illegal employment.
Two further practical points. First, foreign students may only work in the jobs and within the hours allowed by the work-study system, so a second job is usually off the table for them. Second, if you are a Chinese tax resident, income from both jobs is taxable in China, and each employer generally withholds tax on the salary it pays you.
An illustrative scenario
Take a hypothetical case: a foreign engineer holds a work permit sponsored by Company A in Suzhou. At weekends she signs a consulting agreement with Company B and invoices it. Nothing is forged and nothing is hidden, yet the work for Company B falls outside the scope of her permit, which is exactly the Article 43 category of illegal employment. If an exit-entry check picks it up, the exposure is a fine and, in aggravated cases, detention and removal with an entry ban. A permit change — or a second permit applied for by Company B — removes the risk entirely.
In short: two jobs are possible in China, but only inside the scope of your permit. Treat the permit as the boundary, not a formality.
Wang Guan | Co-founder, Beijing Haolue Law Firm | +86 17813108512