Changing your name after marriage or divorce? Why skipping the Social Security office will cost you.

Nearly 4 in 10 divorces are between people 50 and older, a rate that has soared in the past decade or so.

There's no clear reason why aging Americans are splitting up, but one possibility is that the prospect of a longer lifespan is pushing them to embrace their bonus years with a sense of freedom.

One step that often slips through the cracks during the messiness of the divorce process is updating your name with the Social Security Administration (SSA) if you legally change it in your divorce decree.

This week, the Social Security Administration sent out a revised how-to sheet about the process.

Divorce after 50 is one of the biggest financial transitions a woman can face, Debra Taylor, a wealth adviser and a certified divorce financial analyst at Carson Wealth in Franklin Lakes, N.J., told Yahoo Finance.

"The Social Security name change is the first domino. The DMV, passport office, and banks need your name to match Social Security's records, and so does Medicare, which many of these women are only a few years away from," she said.

Your Social Security number will not change; only the name linked to it will.

If you're still working, a name mismatch on your W-2 can keep earnings from being credited to your record, Taylor added. "At 55 or 60, every one of those years counts."

Of course, it's not only if you're divorced. If you legally change your name because of a new marriage, you also must notify the SSA to get a replacement Social Security card with your correct legal name.

Here's why: The Department of Motor Vehicles and the US State Department often validate your identity against SSA databases before issuing a new driver's license or passport in your new name. And the IRS checks your name against SSA records. A discrepancy between your tax return and your Social Security number can also delay your tax refunds.

Make sure your final divorce decree or marriage certificate explicitly states your new legal name. Otherwise, you may have to file a separate legal name change petition through your local courthouse.

Once you have that document and an unexpired US photo ID, such as your driver's license or passport, you can fill out an application for a revised Social Security card. You can submit the form and your original certified documents either by mail, online, or in person at your local Social Security office.

It's a hassle to some extent, but changing your name with the SSA is free. So that's good news. A replacement card typically arrives by mail within two weeks.

"Always be sure to check your 'my Social Security' account afterward to confirm your name and earnings record are correct," Taylor added.