The answer I got from the tax department is that you should declare according to 2% of your total salary last month, not from the day when the trade union was established! Whether or not a trade union is established, as long as there is a real salary in that month, it is necessary to declare trade union funds! The difference is that enterprises that have established trade unions can allocate a certain proportion of trade union funds in the grass-roots trade union organizations where your unit is located, while enterprises that have not established trade unions will not allocate them back!