Income and deductions
Gross annual income; social insurance entered monthly.
Enter annual income, social insurance and deductions to get the tax due. Switch the bonus between separate taxation and merged, and see which is cheaper.
Open Income Tax & Bonus →Gross annual income; social insurance entered monthly.
Enter 0 if you do not receive one.
The difference tells you which way to declare.
Use Manlin to reflect, plan and take your next step.

It is an estimate only; special deductions and other income change the result — the tax system prevails.
Neither. Lower incomes often benefit from merging; larger bonuses usually benefit from separate taxation.