As a CPA, I Thought I Knew Social Security – Until I Retired. Here are 5 Costly Mistakes Even Professionals Make.

I am a CPA and financial writer with over 30 years of experience, including writing dozens of articles about Social Security.

But when it came time to file for my own Social Security last year, I had to pause.

I thought I knew the program inside and out. But when I moved from the theoretical side of the desk to the retired side, I realized that the system is full of invisible triwires.

There are tax breaks that are not indexed to inflation. There are job restrictions that can limit your benefits. There are various myths that sound smart but are actually mathematically illiterate.

If a CPA can stumble over these rules, I know it happens to everyone. Here are five stupid mistakes I see retirees make – and how I avoided them.

1. Breaking a common tax myth

Most people think that since they pay taxes on their earnings before they go into Social Security, their benefits will not be taxed.

That’s a reasonable assumption, but it’s only true if you have very little other money.

If you have other sources of income — such as a pension, withdrawals from a 401(k) or even a part-time job — you’ll likely turn on a tax formula often called temporary income.

The IRS takes your adjusted gross income, adds any tax-free interest and adds a portion of your Social Security benefits. If that number is more than $25,000 (for single filers) or $32,000 (for those married filing jointly), you owe up to 50% of your earnings in taxes. If it exceeds $34,000 for individual filers or $44,000 for joint returns, you owe taxes on up to 85% of your earnings.

Here’s the kicker: These limits were set in the 1980s and have not been adjusted for inflation. They were meant to tax the rich, but today, they hit the middle class. Be prepared for this tax bill because it catches many people off guard every year.

2. Too much focus on age

When I told my friends that I was thinking about delaying my benefits claim until I was 70, they all said the same thing: “But what if you die?”

They took out the napkins and calculated my retirement age – the years I have to live in order for the big checks to beat the smaller, earlier ones. In general, statistics say you have to live to 80 to be in your prime.

Here’s the problem with that calculation: It assumes you’ll die young.

According to the actuarial tables of the Social Security Administration, if you are a man who has already reached 65, your average life expectancy is another 18 years (83 years). If you are a woman, about 21 years (86 years).

If you claim early at age 62 to “get yours” and live to 90, you’re worth tens of thousands of dollars in guaranteed, inflation-protected income. Unless you have a serious health problem, betting on your early death is a bad financial strategy.

3. Working hard (salary check)

I have a friend who claimed benefits at age 63 but kept his consulting gig. He thought he was double dipping. Then she got a letter from the SSA telling her they were holding her checks.

You have breached the income test.

In 2026, if you claim benefits before your full retirement age, you can only earn $24,480 a year. For every $2 you earn above that limit, the government withholds $1 of your benefits.

They don’t take it forever. They end up recalculating your benefit when you reach full retirement age to pay you, but that doesn’t help you pay your electric bill today. If you plan to continue working, don’t apply early if you don’t need to.

4. Strengthening your spouse

I earn a lot from my household. If I file early, I permanently deposit the survivor benefit that my wife will receive if I die first.

When the higher earner dies, the lower earner gets a bump in the paycheck of the higher earner. But if the top earner takes a reduced check at 62, the surviving spouse is stuck with that reduced amount for life.

When you earn a lot, you’re not just holding yourself back. You are buying your spouse a lifetime high.

5. Setting it and forgetting it

Social Security is not a “set it and forget it” income.

Every year, there is a cost of living adjustment (COLA). In 2026, it is 2.8%. But Medicare Part B premiums also go up, and are deducted directly from your paycheck.

I check my personal “social security” account online every year. I check the payroll record to make sure they haven’t missed a year of work (which happens more than you think). And I check my withholding settings.

If you don’t ask the SSA to withhold taxes from your check (form W-4V), you may receive a larger tax payment in April. For many, it’s less painful to be withheld every month than to write a big check to the IRS once a year.