Last month, Social Security celebrated its 87th "birthday." Since being signed into law in August 1935 and beginning payouts on Jan. 1, 1940, Social Security has served as a financial foundation for our nation's retired workforce.

Today, more than 48 million retired workers are receiving a monthly check that averages $1,670.95, as of July. While this might not sound like a lot -- especially with inflation at four-decade highs -- Social Security plays a key role in helping recipients make ends meet. According to national pollster Gallup, 89% of surveyed retirees count on Social Security as a "major" or "minor" source of income. This means only about one in 10 Americans aren't reliant on Social Security income during retirement.

President Joe Biden happens to fall into this exclusive club.

Joe Biden smiling while standing in the East Room of the White House.

A smiling President Joe Biden standing in the East Room. Image source: Official White House Photo by Adam Schultz.

Here's how much Social Security income Joe Biden is receiving

Since the early 1970s, most U.S. presidents have chosen to publicly file their federal tax returns. This has been the case with Joe Biden prior to and following his November 2020 election victory.

While there are numerous income streams to note on President Biden's tax return, which is jointly filed with his wife Jill Biden, the eye-popping income figure to note can be found on line 6a of Form 1040. For those who aren't tax professionals, line 6a is where an individual or couple filing jointly would list the amount of Social Security benefits they received in the previous calendar tax year (in this instance, 2021).

Last year, the Biden's claimed $54,665 in Social Security income on a joint basis, which works out to about $4,555 each month. Even taking into account that this $4,555 figure is the combination of Joe's and Jill's monthly payout, this is well above what the average retired worker brings home each month from Social Security.

Furthermore, with the U.S. inflation rate hitting a more than four-decade high of 9.1% in June, the 2023 cost-of-living adjustment (COLA) for Social Security should be sizable -- i.e., the largest in decades. Following a 5.9% COLA that was passed along to beneficiaries in 2022, it wouldn't be a surprise to see the Biden's taking home well in excess of $60,000 a year, jointly, from Social Security come their 2023 federal tax filing.

High earners face a Social Security payout cap

On one hand, $54,665 ($4,555/mo.) is a sizable chunk of change to receive annually, relative to the average Social Security check doled out to retired workers. But when compared to the Bidens' combined income history, things look a bit different.

According to archived tax returns, the adjusted gross incomes (AGIs) for the Bidens fluctuated between $210,797 and $407,009 from 1998 through 2016. The president and his wife brought home a staggering $11,031,309 in 2017 and $4,580,437 in 2018, on a combined basis. In other words, the couple's Social Security joint payout is actually quite small compared to what the duo brought home in AGI each year over a two-decade stretch.

The reason their collective payout seems so low relative to their combined AGIs is that the Social Security program caps monthly checks.

To calculate a retired worker's monthly check at full retirement age, the Social Security Administration will take an individual's 35 highest-earning, inflation-adjusted years into account. Because the Bidens have earned so much over multiple decades, they've likely neared or achieved Social Security's maximum monthly payout.

In 2021, the maximum Social Security check for a worker at full retirement age was $3,148 a month. Whether you earned an average of $200,000 or $10 million annually over 35 years made no difference -- $3,148 a month was the maximum monthly benefit at full retirement age in 2021.

A Social Security card wedged between U.S. tax forms, with eyeglasses and a twenty-dollar bill set atop the tax forms.

Image source: Getty Images.

Chances are you're going to pay tax on your Social Security benefit

The other noteworthy figure on Joe and Jill Biden's most recent federal tax return can be found directly adjacent to the amount of reported Social Security benefits. Line 6b lists $46,465 in taxable Social Security income.

That's right, folks...Social Security benefits are taxable under certain circumstances.

In 1983, with Social Security's asset reserves dwindling, Congress passed and President Ronald Reagan signed the last sweeping overhaul of the program. Among the many changes made was the introduction of the taxation of benefits, which took effect in 1984.

The Social Security Amendments of 1983 subjected half of an individual's Social Security income to federal taxation if their modified adjusted gross income (MAGI) plus one-half of benefits received surpassed $25,000 (or $32,000 for couples filing jointly).

A decade later, in 1993, President Clinton oversaw the addition of a second tier of taxation, which allowed up to 85% of an individual's or couple's Social Security payout to be taxed at the federal rate. The income threshold for this upper tier, using the same MAGI plus one-half benefits received formula, is $34,000 for individual filers and $44,000 for joint filers.

As you'll note, the Bidens earn far more than the top-tier income threshold, which exposes 85% of their Social Security income to federal taxation each year.

Additionally, it's worth pointing out that these income thresholds tied to the taxation of benefits have never been adjusted for inflation. As monthly Social Security checks have increased with inflation over time, more and more seniors are being exposed to some form of tax liability on their Social Security income. This is unlikely to change anytime soon.