Many older Americans are pleasantly surprised when they receive their first Social Security check. According to a new study from the National Bureau of Economic Research (NBER), people tend to underestimate the amount of their future benefits and wind up receiving more than they expected.

Social Security: No Matter Your Age, Do Not Claim Benefits Until You Reach This Milestone
Learn: 3 Ways To Recession-Proof Your Retirement

But while more money is always welcome, any incorrect assessment of Social Security can throw a wrench in retirement planning and invite unwelcome surprises.

Recipients Are Accurate About Age — Amount, Not So Much

The NBER study found that older adults tend to accurately assess the age they’ll claim Social Security, but lowball the benefit amount they anticipate receiving — and many are way off.

The average person underestimates their benefit amount by $1,896, an 11.5% miscalculation relative to the average benefit received — but 25% misjudged their benefits by $5,167 or more.

On the other end of the spectrum, 10% overestimate their benefits by at least $5,319.

Retirement Savings: Here’s How Much Cash Baby Boomers Need To Retire in the Next 5 Years

Who Could Stress About Getting More Than They Had Planned?

Winding up with a bigger monthly check than you expected is not ideal — accurate retirement planning is. One danger of lowballing your benefits is that a bigger Social Security payment could increase your taxable income and actually cost you money in retirement.

But there are more immediate risks to consider.

“If seniors underestimate their Social Security benefits, they might be saving more than necessary or living too frugally, missing out on the quality of life they could have in their retirement,” said Dennis Shirshikov, a finance professor at the City University of New York and head of growth at Awning.com. “On the other hand, it could push some into risky investments in an attempt to boost their retirement income.”