Union dues are typically a percentage of pay—usually between 1.5% of pay to as much as five percent of pay.
The amount of union dues vary from union to union and will usually range from a few hundred dollars per year to more than a thousand dollars, and sometimes even higher.
You should also know that, if you do not live in a Right to Work state, you can be required to pay union dues (or agency fees) or the union can order you to be fired if there is a union (income) security agreement in your place of work.
To read more about forced union dues/fees, go here.
In addition, union dues are not the same as initiation fees that can be charged to join the union (also usually in the hundreds of dollars); nor are dues the same as “special assessments” (which is money members may be required to pay in addition to normal monthly dues).