For years, we used to talk about a “three-legged stool” for retirement income — a company pension, Social Security and personal savings.

But traditional company pension plans that provide a guaranteed monthly income for life are nearly a thing of the past.

Roughly 15% of private-sector workers in the United States have access to a traditional defined benefit pension plan, as most employers have made the transition to 401(k)-style defined contribution plans.

This leaves Social Security as the only part of retirement income that provides a stable monthly benefit designed to last for your lifetime, making it important to choose wisely about when to start collecting.

For those born in 1960 or later, the full retirement age (FRA) for Social Security is 67.

While you can claim reduced benefits as early as age 62, waiting until 67 provides 100% of your benefit, and delaying up to age 70 increases your monthly benefit.

Click here for the Social Security Administration’s details on your earnings history and expected benefits.

The big question is whether you should wait to take full benefits at age 67, start earlier with reduced benefits, or wait until age 70 to get bigger benefit checks.

The Social Security Administration website provides a chart showing percentages of “primary insurance amount at different ages depending on your year of birth.

Assuming you were born in 1960 or later (most of us born earlier are already receiving Social Security), benefit percentages are 70% at age 62, 100% at age 67, and 124% at age 70.

So, which is the better choice? Well, it depends on several factors, including your personal financial situation, marital status, whether you’re still working, health and longevity, and spousal benefits.

Let’s look at these:

Financial Situation

Your cash needs can impact the decision. If you need your Social Security benefits to make ends meet, you have fewer options and may need to start taking benefits early.

But you may want to consider postponing retirement by working longer to maximize your benefits.

Note: If you take benefits before normal retirement age (67), earnings from work can reduce your benefits by $1 for every $2 you make.

Marital Status

If you’re married, consider your spouse’s age, health and their own benefits — especially if you’re the higher earner.

For example, at full retirement age, you can take either 100% of your own benefit or 50% of your spouse’s benefit, whichever is higher.

Health and Life Expectancy

Taking Social Security earlier reduces your benefits, but you’ll get them for a longer period of time.

On the other hand, delaying results in fewer Social Security checks over your lifetime, but each check will be larger.

According to SSA, the average life expectancy for a 65-year-old is around 84 for men and 87 for women.

And note that married individuals tend to live even longer, with an average probability of at least one spouse living to age 90.

Most benefit calculators I’ve seen or used suggest the advantage of delaying the start date if you live longer than average expected life expectancy.

If you and your spouse are both healthy, that might be a good bet, but certainly no one has a crystal ball that can predict who long you’ll actually live.

Note: Some worry about Social Security’s financial health. For years, the Social Security Board of Trustees has warned against a projected shortfall that would require the program to reduce benefits to participants by about 17% after 2035.

That is, of course, only if Congress fails to act. The most obvious solutions include raising the retirement age, increasing the payroll tax rate, or both.

My personal decision was to wait for maximum age 70 benefits, hoping my good health would see bigger checks coming in for a long time, and leaving higher benefits to my wife if not.

Given the importance of this decision and the number of variables that should be considered, getting help from a skilled financial planner and tax professional can be smart.