How IRS Form 5329 Part I Calculates the 10% Additional Tax on Early Retirement Withdrawals

If you pull money out of a 401(k) before you turn 59½, the IRS usually wants a 10% penalty on top of the regular income tax you already owe. IRS Form 5329, Part I, is the form that actually does this math, and it's also where you can claim an exception that shrinks or wipes out that penalty. Here's a walk-through of how the form's logic works, using a simple early 401(k) withdrawal as the example.

What counts as an 'early' distribution

The IRS defines an early distribution as any distribution taken from your IRA, other qualified retirement plan, or modified endowment contract before you reach age 59½. This definition covers more than just IRAs — it also applies to 401(k) plans, 403(a) annuity plans, and 403(b) tax-sheltered annuities, all of which fall under the IRS's umbrella term 'qualified retirement plan'. That matters because the exceptions available to you on Form 5329 depend partly on which type of account the money came from. A distribution from a 401(k) can qualify for different exceptions than the same dollar amount pulled from a traditional IRA, even though both are early distributions in the IRS's eyes.

How Part I of the form is built

Form 5329's Part I generally applies the 10% additional tax to the taxable portion of an early distribution from a 401(k), other qualified retirement plan, IRA, or modified endowment contract, though qualified disaster recovery distributions are excluded and SIMPLE IRA distributions taken within the first 2 years of participation are taxed at 25% instead. That taxable amount is reduced by any amount that qualifies under one of the numbered exception codes before the 10% rate is applied to what remains.

Line/Field	What it captures	Why it matters
Line 1 — Early distribution amount	The taxable portion of the distribution that is includible in income	This is the starting figure the 10% tax will apply to
Line 2 — Exception amount and code	The dollar amount excluded under one of the numbered exception codes (01–23, or 99 if more than one applies)	Reduces or eliminates the amount subject to the additional tax
Line 4 — Additional tax	Generally 10% of the includible amount after subtracting any exception	This is the penalty amount added to your tax bill, except SIMPLE IRA distributions within the first 2 years of participation, which use 25% instead of 10%

How Form 5329's Line 1, Line 2, and Line 4 work together to turn your withdrawal amount into a final penalty figure.

Worked example: a $10,000 early 401(k) withdrawal with no exception

Say you're 45 and you take a $10,000 distribution from your 401(k) with no rollover and no exception. On Line 1, you'd enter the full $10,000 as the early distribution amount, since that's the portion includible in income. Because you separated from your job well before the year you turned 55 and haven't completed 25 years of service under the plan, you don't qualify for the Rule of 55 exception, so Line 2 would be zero. That leaves the full $10,000 on Line 3, and multiplying by 10% gives you $1,000 as the additional tax on Line 4.

• withdrawal: 10000
• exception amount: 0
• Formula: withdrawal - exception amount
• Result: 10000

With no exception claimed, the full $10,000 early 401(k) withdrawal is subject to the 10% additional tax.

Worked example: the same $10,000 withdrawal using the Rule of 55

Now imagine you separated from your employer in the year you turned 56, and the $10,000 came from that same employer's 401(k). Because your separation from service happened in or after the year you turned 55, you can enter exception code 01 — commonly called the Rule of 55 — on Line 2, and it does not apply to IRAs, only to qualified plans like a 401(k). If the entire $10,000 qualifies under this exception, Line 2 equals $10,000, Line 3 drops to zero, and Line 4 — the additional tax — comes out to $0.

• withdrawal: 10000
• exception amount: 10000
• tax rate: 0.1
• Formula: (withdrawal - exception amount) * tax rate
• Result: 0

If the Rule of 55 applies to the full withdrawal, Line 2 offsets Line 1 entirely and the additional tax on Line 4 is zero.

Other exceptions that can reduce the tax on Line 2

The Rule of 55 isn't the only way to reduce or eliminate the tax, and the form lists 23 numbered exception codes you can enter on Line 2, with code 99 reserved for when more than one exception applies to the same distribution. For a 401(k) specifically, one relevant option is exception code 05, which excuses the portion of a distribution equal to unreimbursed medical expenses you paid during the year that exceed 7.5% of your adjusted gross income for that year. So if you had $4,000 in unreimbursed medical bills and your AGI put 7.5% of it at $2,500, you could enter $1,500 on Line 2 under code 05, and only $8,500 of the original $10,000 would be taxed at 10%. The emergency personal expense distribution exception (code 23), available for distributions made after December 31, 2023, caps out at $1,000 per calendar year and limits taking another such distribution in the following 3 years unless you repay it or make subsequent contributions. It's worth noting that some exceptions only work for certain account types — code 06 (QDRO) applies to qualified plans but not IRAs, while codes like 07 (health insurance premiums), 08 (higher education), and 09 (first-time homebuyer) apply only to IRAs and not to 401(k)s.

Why the 401(k) and IRA math can diverge

It's tempting to assume all early retirement withdrawals get treated the same way, but Form 5329's exception list draws a hard line between plan types. A person who left their job at 56 and pulled money from that employer's 401(k) can use the Rule of 55, but if they'd rolled that money into an IRA first, the same exception would no longer apply. On the flip side, someone taking an early IRA withdrawal for a first home or tuition bill has options a 401(k) holder doesn't have on that account, at least not without a rollover first. And SIMPLE IRAs have their own wrinkle: distributions taken within the first two years of participation are taxed at 25% rather than 10%, a rate that doesn't apply to standard 401(k) withdrawals at all. Knowing which bucket your money sits in before you withdraw it can change how much of the 10% additional tax you end up owing.

Key takeaways

• The 10% additional tax generally applies to the taxable portion of an early distribution from a 401(k), other qualified plan, IRA, or modified endowment contract taken before age 59½.
• Form 5329 works in a simple sequence: Line 1 is the taxable distribution, Line 2 is any exception amount, and Line 4 applies 10% to what's left after subtracting Line 2 from Line 1.
• There are 23 numbered exception codes, and code 99 is used when more than one applies to the same distribution, but not every code works for every account type — some, like 01 (Rule of 55) and 06, apply only to qualified plans such as 401(k)s, while others, like 07, 08, and 09, apply only to IRAs.
• The Rule of 55 (code 01) can zero out the tax on a 401(k) withdrawal if you separated from service in or after the year you turned 55 (age 50 for qualified public safety employees and private-sector firefighters), or after 25 years of service under the plan, whichever is earlier, but it does not apply to IRAs.
• SIMPLE IRA withdrawals in the first two years of participation are taxed at 25%, not 10%, which is a different calculation entirely from the 401(k) example above.

Frequently asked questions

Does the 10% tax apply to the whole withdrawal or just part of it?

It applies only to the part of the distribution that's includible in income, which is entered on Line 1 of Form 5329.

What's the difference between an exception and just not owing income tax on the withdrawal?

An exception entered on Line 2 excludes the corresponding amount from the 10% additional tax calculation on Form 5329.

Can I use the Rule of 55 if I rolled my 401(k) into an IRA first?

No. The Rule of 55 exception applies only to qualified retirement plan distributions and specifically does not apply to IRAs. That said, other exception codes on Form 5329 apply only to IRAs, such as code 07 for health insurance premiums, code 08 for higher education expenses, and code 09 for first-time homebuyer expenses.

How does the medical expense exception change the math in the worked example?

Exception code 05 lets you exclude, up to the amount of the qualified retirement plan distribution, the unreimbursed medical expenses you paid during the year that exceed 7.5% of your adjusted gross income for that year.

Is the emergency personal expense exception enough to cover a $10,000 withdrawal?

Not on its own. This exception is capped at $1,000 per calendar year. There are also limits on taking this exception again in the following 3 years unless you repay it or make subsequent contributions, and it only applies to distributions made after December 31, 2023.

Sources

• www.irs.gov
• www.irs.gov
• www.irs.gov