Alliant Energy 401(k) Plan

Officially: ALLIANT ENERGY CORPORATION 401(K) SAVINGS PLAN

The Alliant Energy Corporation 401(k) Savings Plan is a defined contribution plan serving 2,987 active participants at year-end 2024, with total plan assets of $1.409 billion. The plan is administered by the Alliant Energy Corporation Benefit Plans Committee and maintained by Fidelity Management Trust Company as trustee. The plan features automatic enrollment with age-based target-date investing, a 50% match on the first 8% of pay, and a non-elective basic contribution ranging from 4% to 6% based on age and service.

Participants: 4,517 Plan assets: $1,409,016,019 Plan number: 005 Form 5500 plan year: 2024 Last verified: Jun 16, 2026 View Form 5500
Match
50% on 8%
Vesting
Employees are immediately vested in employee and matching contributions; basic contributions are subject to a three-year cliff vesting schedule.
Self-Directed Brokerage
Brokerage window available
Investment Options
15 funds
Auto-Enrollment
An initial automatic 8% pre-tax deferral is applied to newly hired full-time eligible employees unless they elect otherwise within 30 days; automatic deferral increases by 1% annually until reaching 10%.
Plan Size
$1,409,016,019

By Zac Murphy, CFA charterholder and CFP professional. Published June 16, 2026. Verified against Form 5500 plan year 2024.

Get a personalized look at your Alliant Energy 401(k) options

Not sure if you're getting the most out of your plan? Tell us a bit about your situation and we'll help you understand your options.

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Fund lineup

Fund Asset Class Type
American Funds EuroPacific Growth Fund, R6 shares International Equity Active
Dodge & Cox Stock Fund, class X shares US Large Cap Active
Vanguard Short-Term Inflation-Protected Securities Index Fund, Admiral shares TIPS Index
Fidelity Investments Money Market Government Portfolio, class I shares Money Market Active
State Street S&P 500 Index Securities Lending Series Fund, class II shares US Large Cap Index
Winslow Large Cap Growth Fund, class C shares US Large Cap Active
Northern Trust Collective Extended Equity Market Index Fund - Lending US Mid Cap Index
BlackRock Total Return Bond Fund, class L shares US Bonds Active
State Street U.S. Bond Index Securities Lending Series Fund, class XIV shares US Bonds Index
JPMCB Intermediate Bond Fund US Bonds Other
JPMCB Intermediate Income Bond Fund US Bonds Other
State Street Global All Cap Equity Ex-U.S. Index Securities Lending Series Fund, class II shares International Equity Index
Earnest Partners Smid Cap Core Fund, class I shares US Mid Cap Active
Alliant Energy Corporation Common Stock Company Stock Other
Self Managed Brokerage Accounts Other Other

Your plan includes a self-directed brokerage window

A self-directed brokerage window is a feature within your 401(k) plan that lets you invest a portion of your balance outside the standard fund menu, into individual stocks, ETFs, or a broader universe of mutual funds. The brokerage window is a separate sleeve within your plan, but money held there remains inside your 401(k) and retains its tax treatment.

Who uses it

  • Participants who want exposure beyond the plan's core menu, such as specific sector ETFs, individual stocks, or low-cost index funds not offered in the menu.
  • Participants who want to consolidate the management of their 401(k) alongside other investment accounts.
  • Participants with meaningful balances who want more direct control over allocation.
  • Self-directed accounts can be actively managed by the participant directly, or by an advisor if the participant chooses to work with one.

Important considerations

  • Additional costs. Brokerage windows often carry additional fees, and trading commissions vary by provider and security type.
  • Allocation limits. Many plans cap the percentage of your balance that can be moved into the brokerage sleeve. Some require a minimum balance in the core menu.
  • Plan rules still apply. Loan and distribution rules, vesting schedules, and contribution limits are unchanged. The brokerage window changes what you can invest in, not the underlying retirement account rules.
  • Confirm details with your plan administrator. The specifics of your plan's brokerage window, including which securities are eligible and any account-level fees, are governed by your plan documents.

Why our allocations use only index funds

The actively managed funds in this plan cost more per year than the plan's index funds, which run roughly 0.02% to 0.06%. Decades of research on long-term active fund performance do not support reliable outperformance net of fees, which is why the allocation ideas below may consider using only the low-cost index options.

Employer match

Match summary
50% match on the first 8% of eligible pay, plus a non-elective basic contribution of 4% to 6% based on age and years of service (less than 49 receives 4%, age 50-69 receives 5%, age 70+ receives 6%)
Match cap 50% of pay
Effective match rate 8%
Vesting Employees are immediately vested in employee and matching contributions; basic contributions are subject to a three-year cliff vesting schedule.
Waiting period Eligible employees aged 18 and over may participate immediately following 30 consecutive days of service with respect to
$
Contribute this much to capture the full match
50% of your eligible pay, every paycheck.

50% match on the first 8% of eligible pay, plus a non-elective basic contribution of 4% to 6% based on age and years of service (less than 49 receives 4%, age 50-69 receives 5%, age 70+ receives 6%) Contributing less than 50% of your eligible pay leaves part of Alliant Energy's match unclaimed.

What the match is worth at your pay After 1 year of service, contributing 50%
Annual pay Your contribution Employer match Total to 401(k)

Estimates assume a constant salary and the match formula shown above. Your actual match depends on your plan's exact terms.

The cost of contributing only --%

On a $60,000 salary, contributing just half the match threshold would leave about -- in employer match unclaimed each year. Invested over 20 years at a hypothetical 7% annual return, that forgone match could have grown to roughly -- (a hypothetical illustration, not a projection). The match is the highest-return contribution you will make all year.

Sources

  • Plan metadata (employer, participants, assets, plan year): Form 5500 annual return/report, plan year 2024 -- view filing
  • Summary Plan Description (SPD) and fee disclosure (404a-5), where available from the plan administrator.

This page is for educational purposes only and does not constitute investment, tax, or legal advice, nor a recommendation to buy or sell any security. Information is drawn from public Form 5500 filings and plan documents and may be incomplete or out of date. You may consider consulting a qualified professional and confirming all details with your plan administrator before making decisions. Waterfall Planning is not affiliated with Alliant Energy.

Find your risk profile

Answer 13 questions to see which allocation fits your situation.

Question 1 of 13

Risk assessment methodology based on Grable, J. E., & Lytton, R. H. (1999). Financial risk tolerance revisited: The development of a risk assessment instrument. Financial Services Review, 8, 163-181.

Allocation ideas

Five sample mixes built from this plan's funds, from conservative to growth. Take the assessment above to see which one fits your risk profile.

Recommended for you (based on your risk profile)
Conservative
Conservative

Capital preservation with minimal market exposure, built from bonds and stable value.

US equity   International   Bonds   Stable value
Vanguard Short-Term Inflation-Protected Securities Index Fund, Admiral shares 70%
Fidelity Investments Money Market Government Portfolio, class I shares 30%
0% stocks / 100% bonds
Recommended for you (based on your risk profile)
Income & A Little Growth
Income & A Little Growth

Mostly bonds with a small stock sleeve for modest growth.

US equity   International   Bonds   Stable value
Vanguard Short-Term Inflation-Protected Securities Index Fund, Admiral shares 49%
Fidelity Investments Money Market Government Portfolio, class I shares 21%
State Street S&P 500 Index Securities Lending Series Fund, class II shares 19%
State Street Global All Cap Equity Ex-U.S. Index Securities Lending Series Fund, class II shares 8%
Northern Trust Collective Extended Equity Market Index Fund - Lending 3%
30% stocks / 70% bonds
Recommended for you (based on your risk profile)
Balanced
Balanced

A classic 60/40 split of stocks and bonds.

US equity   International   Bonds   Stable value
State Street S&P 500 Index Securities Lending Series Fund, class II shares 39%
Vanguard Short-Term Inflation-Protected Securities Index Fund, Admiral shares 28%
State Street Global All Cap Equity Ex-U.S. Index Securities Lending Series Fund, class II shares 15%
Fidelity Investments Money Market Government Portfolio, class I shares 12%
Northern Trust Collective Extended Equity Market Index Fund - Lending 6%
60% stocks / 40% bonds
Recommended for you (based on your risk profile)
Growth & Income
Growth & Income

Stock-heavy with a bond cushion for a long horizon.

US equity   International   Bonds   Stable value
State Street S&P 500 Index Securities Lending Series Fund, class II shares 52%
State Street Global All Cap Equity Ex-U.S. Index Securities Lending Series Fund, class II shares 20%
Vanguard Short-Term Inflation-Protected Securities Index Fund, Admiral shares 14%
Northern Trust Collective Extended Equity Market Index Fund - Lending 8%
Fidelity Investments Money Market Government Portfolio, class I shares 6%
80% stocks / 20% bonds
Recommended for you (based on your risk profile)
Growth
Growth

All stocks for maximum long-term growth potential, with higher short-term volatility.

US equity   International   Bonds   Stable value
State Street S&P 500 Index Securities Lending Series Fund, class II shares 65%
State Street Global All Cap Equity Ex-U.S. Index Securities Lending Series Fund, class II shares 25%
Northern Trust Collective Extended Equity Market Index Fund - Lending 10%
100% stocks / 0% bonds
Stay on track

Get a plain-English breakdown of your plan

Occasional, no-jargon guidance on getting the most from your workplace retirement plan.

  • ✓ What your match is really worth
  • ✓ How to keep costs low with index funds
  • ✓ Plan updates when your filing changes

We send only what's useful. No advisor pitches, no data sales.

These allocation ideas are educational illustrations built from this plan's available funds and a standard risk-tolerance assessment. They are not personalized investment advice or a recommendation, and risk tolerance is only one factor in an investment decision. You may consider consulting a qualified professional before making changes to your account.