When you retire, your base annuity will be computed. If you elect a survivor annuity, the amount of the reduction will be calculated and applied. After that’s done, you will have a new base annuity.
For example, if you are under FERS and your original base annual annuity were $30,000 and you elected a full (50 percent) survivor annuity for your spouse, that figure would be reduced by 10 percent. So your new base annuity would be $27,000. That’s the annuity amount that would be increased each time you were eligible for an annual cost-of-living adjustment. Your new base annuity is not decreased annually to pay for the survivor annuity benefit.
If you died before your spouse did, your spouse would be entitled to the percentage of your annuity that you elected. That percentage would be applied to the annuity you would have been receiving on the day you died had you not elected a full survivor annuity.
Using the example above, if your original base annual annuity were $30,000, your survivor would receive 50 percent (that is, the percentage you chose) of that annuity increased by all intervening COLAs. On the other hand, if your spouse died before you did, your annuity would be increased to what it would have been had you never elected a survivor annuity, including all the intervening COLAs between your retirement and when your spouse died.