Millions of retirees depend on Social Security benefits to pay the bills. In fact, around one in five married couples depend on their monthly checks for at least 90% of their income in retirement, according to the Social Security Administration.

However, Social Security benefits were never intended to be a primary source of income. They were only designed to replace around 40% of your pre-retirement income, and the rest would need to come from your savings, a pension, or some other income source.

If you're nearing retirement age and are realizing you need to supplement your Social Security benefits, you have a few options.

Older couple sitting on a couch looking at documents

Image source: Getty Images.

1. Ramp up your retirement contributions 

It's never too late to save more for retirement. Even if you're nearing your senior years, you may be able to save more than you think.

If you have access to a 401(k) that offers employer matching contributions, try to save at least enough to earn the full match. Depending on your salary and how much your employer will match, you could potentially receive thousands of dollars per year in matching contributions. If you're not taking advantage of this perk, you're leaving free money on the table.

In addition, if you're age 50 or older, you're eligible to make 401(k) and IRA catch-up contributions. Normally, you're allowed to contribute up to $19,500 per year to your 401(k) and $6,000 per year to your IRA. Once you turn 50, however, you can save an additional $6,500 per year in your 401(k) and an extra $1,000 per year in your IRA.

Saving more for retirement when you're down to the wire can be tough. But even if you can't save much, every little bit counts.

2. Consider working longer

Just over half (52%) of Americans say they expect to continue working past age 65 or never retire at all, according to a survey from the Transamerica Center for Retirement Studies. If your savings are falling short, it may be a good idea to consider delaying retirement or picking up a part-time job after you retire.

Even if you're only able to delay retirement by a year or two, that can make a significant difference in your savings. When you work longer, that's less time you'll spend in retirement -- and less you'll have to save. You'll also have more time to prepare for retirement, making it a little easier to boost your savings. 

If you'd rather not delay retirement, you may consider picking up a part-time job instead. Not only can this help you save more, but it can also give you an opportunity to explore a new industry. If you've always been interested in a particular field but didn't want to make it a career, retirement is your chance to try something new. 

3. Delay claiming benefits

Although Social Security benefits alone likely won't be enough to make ends meet in retirement, you can earn larger checks by waiting a little longer to begin claiming.

To receive the full benefit amount you're entitled to, you'll need to claim at your full retirement age (FRA) -- which is either age 66 or 67, depending on the year you were born. If you wait until after your FRA to file for benefits, though, you'll receive up to 32% more each month.

The longer you delay benefits (up to age 70), the more you'll receive each month. If you're having trouble saving, these larger checks can go a long way in retirement.

Social Security benefits can have a significant effect on your retirement, but you'll likely need other sources of income to retire as comfortably as possible. By taking steps to build a stronger nest egg, it will be easier to enjoy your senior years to the fullest.