Unions sometimes attempt to impose limitations upon the right of a member to resign. However, a decision of the Supreme Court in Abood v. Detroit Board of Education, 431 U.S. 209 (1977), a Foundation-supported lawsuit, makes clear that you cannot constitutionally be prevented from resigning from your union at any time. Some states, but not all, also have statutes that guarantee public employees the right to resign.
As a nonmember, you would have a right to object to the amount of the agency fees and obtain a reduction of your compulsory payments so that they do not include the part of dues that is used for purposes other than collective bargaining, contract administration, and grievance adjustment.
The decision to resign is yours alone. In addition to the reduction in your financial obligations to the union, as a nonmember you would not be subject to union rules and discipline. The union would have to continue to represent you fairly and without discrimination in all matters subject to collective bargaining, and you could not be denied any benefits under the labor contract with your employer because of nonmembership.
On the other hand, you would not have the right to vote on ratification of the contract or election of union officers, and there may be benefits provided under the union's constitution or bylaws that are not available to nonmembers (however, a nonmember cannot be charged a share of the costs of member-only benefits).
If you work in a Right to Work state, or neither state law nor the contract between your employer and the union contains a provision requiring you to join the union or pay union fees, after resigning, you would have no obligations whatsoever to the union. (However, if you have signed a dues deduction authorization, that authorization may contain a limitation on when it can be revoked.)
If you would like to see a sample union resignation letter for a Right to Work state, or where neither state law nor the contract requires you to join the union or pay union fees, click here. You should check your union's constitution and bylaws to see if it specifies to whom a resignation must be sent.
If you work in a non-Right to Work state and state law or the contract does contain a provision requiring you to join the union or pay union fees, after resigning you would still have to pay union fees (generally called "agency fees" or "fair share fees").
If you would like to see a sample union resignation/objection letter for a non-Right to Work state where state law or the contract does require you to join the union or pay union fees, click here. You should check with the union to see if it has a policy concerning when and to whom resignation/objections letters should be submitted. For links to union objection policies on the Internet, click here.
Although the sample resignation/objection letter includes the line that says your objection is continuing and permanent, some unions will not honor this and will make you annually renew your objections. The courts have issued inconsistent decisions on this point.