Social Security Survivor Benefits Reflect Delayed Retirement Credits
Social security survivor’s benefits reflect delayed retirement credits, spousal benefits do not.
For married couples this means joint social security benefits are usually maximized when the lower earning spouse begins benefits as soon as possible (as long as those benefits would not be lost due to the earnings test), while the higher-earning spouse delays benefits until age 70.
See Journal of Financial Planning Article Social Security: When To Start Benefits for a detailed analysis.
Switching Strategies Allowed For Social Security Survivor Benefits
As a widow/widower you can begin benefits based on your own earnings record and later switch to survivor’s benefits, or begin survivor’s benefits and later switch to benefits based on your own record.
In contrast, before attaining full retirement age, such switching strategies are not allowed between spouse’s benefits and benefits based on your own record.
You can use a Social Security calculator to accurately model these types of scenarios.
Length of Marriage Requirements Differ Slightly
To claim a social security survivor benefit you must be married for at least nine months; to claim a spousal benefit you must be married for at least one year.