The Social Security math married couples keep getting wrong

Go to ssa.gov, log in, and pull both statements. Yours and your spouse's. Write down two numbers: what each of you would get per month at full retirement age. For anyone born in 1960 or later, that age is 67.

Those two numbers run the whole conversation. Not your account balance, not your advisor's pie chart. Two numbers, and which one of you dies first.

That sounds blunt. It's also the single most useful frame for a married couple, because Social Security doesn't treat a marriage as two separate retirements. It treats it as one household with a built-in insurance policy, and most couples never read the policy.

Spousal and survivor are two different animals

A spousal benefit lets the lower earner collect off the higher earner's record while both are alive. The ceiling is 50 percent of the higher earner's primary insurance amount — the benefit that person would get at full retirement age.

Three things trip people up here.

First, the 50 percent is measured against full retirement age, always. If your husband delays to 70 and earns delayed retirement credits, your spousal benefit doesn't grow with his. Half of his age-67 figure is the cap, period.

Second, you can't claim a spousal benefit until the worker has filed. His claim unlocks yours.

Third, if you file for a spousal benefit before your own full retirement age, it gets cut, and you don't get to pick which benefit you're filing for. Under current rules you're deemed to have filed for both your own retirement benefit and any spousal benefit you qualify for, and you receive essentially the higher of the two. Those old file-and-suspend and restricted-application plays you may have read about in 2014 are gone for almost everybody.

A survivor benefit is a different creature entirely. When one spouse dies, the surviving spouse can step into the deceased spouse's check — up to 100 percent of what that person was actually receiving, delayed retirement credits included.

Read that again. Spousal caps at half of the full-retirement-age amount. Survivor can be the whole thing, grown.

Which means the higher earner's claim date is really a life insurance decision

Whatever the higher earner does echoes for as long as both of you're alive, and then for as long as the survivor is alive after that.

An illustrative example, not a projection. Say a husband's full-retirement-age benefit is $3,000 a month and his wife's is $1,200. If he claims at 62, his check is permanently reduced — call it roughly $2,100 in this example. If he waits until 70, it grows to roughly $3,720.

While both are alive, the household difference is real but survivable. After he dies, it's the difference between his widow living on about $2,100 a month and about $3,720 a month, for however many years she has left. Twenty years of that gap isn't a rounding error.

Those dollar figures are made up to show the shape of the decision. Your actual numbers are on your statement, and the reduction and credit percentages are published at ssa.gov.

There's a limit worth knowing: if the deceased spouse claimed early, the survivor benefit is capped at the greater of what he was actually receiving or 82.5 percent of his full-retirement-age amount. It's a floor that softens a very early claim, and it's exactly the kind of rule nobody explains at the counter.

The widow's penalty is a tax problem too

Here's the part that catches families flat-footed. Two Social Security checks become one. The smaller one disappears; the survivor keeps whichever is larger. Household income can fall by a third or more overnight.

Meanwhile the tax picture gets worse, not better. A widow generally files jointly for the year of the death, then files as single after that, unless she has a qualifying dependent child. Single brackets are narrower. Medicare premiums are means-tested on a single threshold rather than a married one. Less income, taxed harder.

This is why survivor planning belongs in the conversation years before anybody needs it. Roth conversions during the married-filing-jointly years, the order you draw down accounts, whether the pension carries a survivor option — all of it bends around that switch. Ask a CPA or a fee-only fiduciary who works by the hour, not one selling you something with a surrender charge.

The one place survivors get a break

Survivor benefits aren't subject to the deemed-filing trap. A widow or widower can take the survivor benefit first and let her own retirement benefit keep growing until 70, then switch. Or take her own small benefit early and switch to the survivor benefit at her full retirement age.

You get to pick the order. That's a genuine advantage, and SSA staff won't always volunteer it — they'll process what you ask for.

Survivor benefits can start as early as 60, reduced, or 50 if you're disabled. Reduced means reduced for life if you stay on that benefit, so run the two-step plan before you file at 60 out of grief and cash-flow panic.

Remarriage matters. Remarry before 60 and you generally lose the survivor benefit on your late spouse's record. Remarry at 60 or later and you keep it. That's a real financial fact with real consequences for the timing of a late-life wedding, and it's worth knowing before the date is on the calendar rather than after.

Divorced after a long marriage

If the marriage lasted 10 years or more and you haven't remarried, you can generally claim on your ex-spouse's record — spousal while he's alive, survivor after he's gone, on the same terms as a current spouse. If you've been divorced at least two years, you can claim even if he hasn't filed yet.

It takes nothing from him. It doesn't reduce his benefit, or his new wife's. He isn't notified. A lot of women leave this money sitting there because they assume the divorce closed the door.

What to actually do this month

• Pull both statements at ssa.gov and write the two full-retirement-age numbers on the same piece of paper. Most couples have never seen them side by side.
• Identify the higher earner. Then treat that person's claiming date as a decision about the survivor's income, not just this year's cash flow.
• Check the pension survivor election if either of you has one. The single-life payout is bigger every month and ends the day you do. That choice is often irrevocable after retirement.
• If either of you worked in state or local government, verify your situation directly with SSA. The rules affecting public-sector pensions and Social Security changed recently, and older articles and calculators are still repeating the old ones.
• Know how survivors apply. You generally can't do it online. It's a phone call or an office visit, plus a death certificate. There's also a modest one-time death payment for a surviving spouse — confirm the current amount at ssa.gov.

Every age, percentage and threshold in this piece can change by act of Congress, and some of them have. Verify against ssa.gov, medicare.gov and irs.gov, and take the actual decision to a fee-only fiduciary adviser, a CPA or an estate attorney who'll look at your numbers rather than a national average. What life after sixty actually feels like day to day is BRO Seniors' beat. This is just the paperwork that keeps it comfortable.

Do it at the kitchen table, both of you, with the statements printed out. One of you is going to have to live with the answer alone. Better she hears it from you now than from a clerk later.