'Social Security is your retirement income anchor': When to claim, explained

You certainly don't have to be an expert on Social Security. But knowing a thing or two about Social Security could greatly improve your chances of having the retirement you desire.

Here's what experts say you need to know.

How much of your pre-retirement income will Social Security replace?

Social Security was never meant to be the only source of income for retirees. But it will replace a percentage of your pre-retirement income based on your lifetime earnings. How much will vary based on your earnings and when you decide to retire.

For instance, if you start benefits in 2021 at your full retirement age, or FRA, this percentage ranges from as much as 78% for very low earners, to about 42% for medium earners, to about 28% for high earners, according to the Social Security Administration's primer on Social Security benefits.

On average, financial advisers say you should aim to replace 70% of your pre-retirement income to live comfortably in retirement. But high earners might need to replace less, and low earners replace more.

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No matter the percent, it's wise to learn how much of your pre-retirement income Social Security will replace. "It's absolutely vital," says Andy Landis, author of "Social Security: The Inside Story."

"For many, Social Security is the bulk of retirement income. For everyone else, Social Security is your retirement income 'anchor.' Think of it as the foundation of all your retirement finances."

Others agree. "I believe that Social Security should be the foundation of everyone's retirement income plan," says Brian Vosberg, a certified financial planner with Vosberg Wealth and author of The Complete Retiree's Guide to Social Security. "It's a government-guaranteed income source that has a built-in cost of living adjustments. Don't underestimate the power of what Social Security can pay you over your lifetime."

What is your FRA?

Knowing when you are entitled to 100% of your Social Security benefits, your primary insurance amount, is critical, experts say. And your FRA depends on your birth year.

For instance, if you were born from 1943 to 1954 your FRA is 66. The FRA then increases gradually if you were born from 1955 to 1960 until it reaches 67. And for anyone born 1960 or later, full retirement benefits are payable at age 67. Use this chart to find out your FRA.