3 Retirement Rules Most People Learn Too Late -- and How to Get Ahead of Them

Retirement planning isn't just about saving money. You also need to know about how much you'll spend each year and create a safe withdrawal strategy to help your savings last the rest of your life.

You can get a rough idea of your retirement costs by looking at your current expenses, but you also have to watch out for a few little-known rules that could trip you up. Ensure you understand the following three things before you leave the workforce, so you don't pay more in retirement than you have to.

Image source: Getty Images.

1. Required minimum distributions (RMDs)

Required minimum distributions (RMDs) are mandatory annual withdrawals you must take from tax-deferred retirement accounts, like traditional IRAs and 401(k)s, beginning in the year you turn 73. The amount you must withdraw depends on your account balance and your age at the end of the year.

These forced withdrawals can raise your taxable income, sometimes by thousands of dollars. This could lead to a larger tax bill than you were expecting, but you can minimize this with careful planning.

You don't have to take RMDs from Roth accounts, so stashing money in one or doing Roth IRA conversions can reduce your future RMDs. However, you'll have to pay taxes on your converted funds in the year of the conversion.

2. Social Security earnings test

Seniors who work while claiming Social Security under their full retirement age (FRA) -- 67 for most workers today -- could lose some of their benefits to the earnings test. This little-known rule reduces the size of your checks when you earn too much from your job.

In 2026, you lose $1 for every $2 you earn over $24,480 if you'll be under your FRA all year. If you'll reach your FRA this year, you only lose $1 for every $3 you earn over $65,160 if you earn this much before your birth month. Once you reach your FRA, the earnings test no longer applies, and you can earn as much as you'd like from a job without it affecting your Social Security checks.

Money lost to the earnings test comes back to you as a permanent benefit boost once you reach your FRA. This increase could be substantial for some, especially if you lost entire checks to the earnings test in years past.

But until then, you may need to plan for smaller benefits. You might have to rely more on your job income or personal savings. Or if you don't need your Social Security checks, consider delaying your application. This gradually grows your checks until you qualify for your largest benefit at age 70.

3. Medicare late enrollment penalty

Your Initial Enrollment Period (IEP) for Medicare begins three months before you turn 65 and ends three months after the month you turn 65. It's crucial to sign up during this window, even if you have other health insurance coverage.

If you don't, your Part B premiums will rise by 10% for each year you could've signed up but didn't. This isn't a one-time payment. It's a lifetime premium increase that could make your retirement healthcare costs a lot more difficult to manage.

There's also a Part D late enrollment penalty, though it works a little differently. You pay an extra 1% per month for failing to sign up, though this doesn't apply if you're a low-income senior who qualifies for Extra Help or if you have comparable prescription drug coverage under another health insurance policy.

These rules could change in the future, especially if you're decades away from retirement. Keep an eye out for any updates, and be ready to adjust your retirement plan as necessary.

The Motley Fool has a disclosure policy.