There are no one-size-fits-all rules when it comes to retirement, and that includes when to begin collecting Social Security checks. Conventional wisdom is to delay benefits until your full retirement age (FRA) -- between 66 and 67, depending on your birth year -- or beyond. Every month you delay increases the size of your checks, until you reach the maximum benefit at 70. So putting it off for a while can net you larger checks and possibly more money over your lifetime.

This makes sense in some situations, but it's not right for everyone. Here are three reasons to consider starting Social Security before your FRA -- even as soon as you become eligible at 62.

Mature woman doing financial calculations

Image source: Getty Images.

1. You don't think you'll live long

Delaying Social Security is only advantageous if you think you'll live a pretty long life. You'll receive larger checks, but you'll get fewer of them, so it takes years to begin out-earning someone who started Social Security at a younger age.

If you have a health condition that will shorten your life or you're just worried you won't live long enough for delaying benefits to be worthwhile, you're better off starting earlier. Your checks will be smaller: You'll get just 70% of your scheduled benefit if you begin at 62 and your FRA is 67 or 75% if your FRA is 66. But you could still end up with more money overall because you'll receive several additional years of checks.

Say you're entitled to a $1,000 monthly benefit at your FRA of 67. If you began at 62, you would only get $700 per month, but you'd have five extra years of checks, so early on, you'll be coming out ahead. By the time you're 70, you'll have received over $75,000 in benefits, compared to just $48,000 if you started at 67.

But things eventually shift the other way. By the time you're 78, you'll have received $142,800 if you began benefits at 62, but you'd have $144,000 if you waited to start until 67, and that gap only widens as you age. But if you don't anticipate making it until your 78th birthday, delaying benefits will only shortchange you.

2. You need the money right now

Whether you're already retired and your savings are dwindling faster than you expected, or you're still working but are currently unemployed due to the COVID-19 pandemic, Social Security can provide additional income right now so you don't have to borrow or fall behind on your bills.

If you only need a little money to hold you over temporarily, you can claim Social Security now and either withdraw your benefit application within 12 months or suspend benefits at your FRA. If you plan to withdraw your application, you must be able to pay back all the money you've received from the program thus far and you must have the written consent of everyone claiming benefits on your work record. You may suspend benefits at your FRA if you're unable to do this. If you choose this route, the government will stop sending you checks until you turn 70 or until you request it to start again. In the meantime, you'll accrue delayed retirement credits, which means larger checks when you do start benefits again. 

You could also just start benefits early and continue claiming them for the rest of your life, but you must be willing to accept smaller monthly checks. Every month you delay increases your benefit, so even delaying a month or two can help if you're worried about shortchanging yourself.

3. You are the lower-earning spouse

Starting benefits early may also be the smarter play if you have earned less money than your spouse over your working life and your spouse intends to delay benefits until FRA or beyond. Starting benefits early can provide an extra source of income to get you through until your spouse is ready to claim benefits.

When your spouse finally does begin claiming benefits, the Social Security Administration will switch you over to a spousal benefit if this would give you a larger sum than you're entitled to based on your own work record.

When you start Social Security is a big decision, and it isn't always obvious when the best time is. But if any of these three scenarios apply, you may be better off starting benefits sooner rather than later. You get steady income to help you through the next few challenging months and the years beyond, even if it means you may get less overall.