In order to qualify for derivative widow (widower) Social Security benefits, a couple must have been married for at least 10 years and the contributing spouse must have been fully insured through Social Security at the time of his death (the contributor must have paid into the system for at least 40 quarters).
In order to qualify for widow benefits, a surviving divorced spouse must be at least 60 years of age (or at least 50 years if disabled), and not have remarried again before age 60.
To prevent a loss of survivor benefits a former spouse who is nearing age 60 and considering remarriage should delay the wedding until after their 60th birthday. However, remarriage doesn't preclude eligibility for disabled surviving spouses or disabled divorcing spouses who remarry between ages 50 and 59.
Unlike what is received by way of derivative benefits on account of a former spouses still living - which is 50%, upon the former spouse's death the derivative spouse is entitled to 100% of the benefits the former spouse was receiving. What a widow receives depends upon their age: This amount is between 70% at age 60 and 100 % at age 65.