Shall the company pay Trade Union expenditure?---Denise Xia

One of our client’s companies got a notice from the Tax Bureau that Trade Union expenditure shall be paid accordingly. And the Trade-Union expenditure being paid is 2% of the employees’ wage, which is not a small cost.
So what is Trade Union? 
It is a union organized by the people who have the same interest on the purpose of negotiating the salary, work time and work condition with the employers.
What kind of people or company shall pay the Trade Union expenditure?
According to Trade Union law of the people’s republic of China, ChapterⅴTrade-Union funds and Property, Article 42 The source of Trade Union fund;
The source of Trade Union fund includes:
1. Membership dues paid by union members;
2. The units established Trade-Union organization press 2% of all employees’ wage to the Trade Union, or pay through Tax Bureau.
3. Paid income from the enterprise or public institution belongs to Trade union.
4. Government allowance.
5. Others income. 
So, if the company didn’t join Trade Union, no obligation to pay Trade Union expenditure. Except as otherwise the cities has provided by law.