If you have a duty to pay spousal support to your ex, under either a separation agreement or by court order, then you will naturally be interested to determine when that duty ends.
First of all, the agreement or court order may be time-limited, or else specify an end date. It may refer to a set number of years, specify a calendar date, or refer to some unknown future point when your ex retires or remarries. Or it may have a review date, which allows for reflection on whether the spousal support amount should be amended or terminated outright.
If no end date is specified – meaning it is “indefinite” – then you and your ex can agree to amend the agreement, or else you can go to a court to have the agreed-upon end date imposed.
This happens only rarely, since you and your ex may be unlikely to agree. In that case, you may need to go to court to have your differences resolved. A court will consider whether there has been a “material change in circumstances” that dictates that the original order or agreement should be varied.
Note that if you are paying support to your ex, then your duty ends when he or she dies. However, it does not automatically end if your ex: 1) retires; or 2) marries or moves in with someone else. Nor does it automatically end if you: 1) retire; 2) marry or move in with someone else; or 3) pass away (for example if you have arranged for life insurance benefits to be paid as a means of continuing support).
Again, in these circumstances, a court will examine whether these amount to a material change that will justify terminating your support obligations.