401(k) · DOL Form 5500 · 2024

Alliant Energy Corporate Services, Inc. 401(k) Plan

Data updated 2026-08-25

$1.4B
Total assets Very large vs avg
3,265
Participants Above avg headcount
99th
Percentile by assets National rank
$431,552
Avg per participant High balance/head
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Official DOL plan name: Alliant Energy Corporation 401(k) Savings Plan · Sponsored by Alliant Energy Corporate Services, Inc. · Wisconsin · Utilities

$1.4B in assets, 3,265 participants

Alliant Energy Corporate Services, Inc.'s Alliant Energy Corporation 401(k) Savings Plan reported $1.4B in total assets and 3,265 participants in its 2024 DOL Form 5500 filing, ranking in the 99th percentile by assets among filed plans. Figures are as reported by the plan sponsor to the Department of Labor, not audited or endorsed by PlainRetire.

  • #666 in Utilities (732 peers)

Coverage in Wisconsin

Alliant Energy Corporation 401(k) Savings Plan covers 3,265 participants in Wisconsin, 5.8x the typical Wisconsin plan (state average ~563 per filing). Assets: $1.4B.

#666
in Utilities (732 peers)
+6.6%
assets growth YoY
14×
vs typical plan assets (national mean)

Alliant Energy Corporation 401(k) Savings Plan's outsized position by total assets

Alliant Energy Corporation 401(k) Savings Plan vs every filed plan by assets

End-of-year total assets · plan year 2024 · DOL Form 5500

$1,409,016,019 Top 1% higher than 99% of 123,620 filed plans

This plan $0 $2,050,000,000 every filed plan with reported assets, bucketed by value

Dashed line + filled bar = this entry, among filed plans.

Source U.S. Department of Labor Form 5500 filings (EBSA) · plan year 2024

Alliant Energy Corporation 401(k) Savings Plan's large-plan peer group by participant headcount

Plan-year 2024 Form 5500 filings with a reported participant count, partitioned by headcount band, not by assets. Alliant Energy Corporation 401(k) Savings Plan lands in the large band (3,265 participants).

What changed between DOL Form 5500 filings

plan year 2023 → plan year 2024

  • Alliant Energy Corporation 401(k) Savings Plan reported net income fell from $155M in the plan year 2023 filing to $88M in the plan year 2024 filing.
  • Alliant Energy Corporation 401(k) Savings Plan end-of-year assets rose from $1.3B in the plan year 2023 filing to $1.4B in the plan year 2024 filing.
  • Alliant Energy Corporation 401(k) Savings Plan reported participants rose from 3,101 in the plan year 2023 filing to 3,265 in the plan year 2024 filing.

See the national 2023→2024 release diff →

Plan-year Form 5500 strip

Filing strip 391914946 · Alliant Energy Corporate Services, Inc. PY 2024 · 401(k)

Alliant Energy Corporation 401(k) Savings Plan · $1.4B · 3,265 · 99th

  • EOY $1.4B
  • EOY 3,265
  • EOY 99th
  • EOY 401(k)
  • EOY near Avaya Savings Plan for Salaried Employees
  • EOY ind #666

Stamps derive from this plan's Form 5500 line items (assets, participants, type, EIN, cohort placement) - not a quality rating of the sponsor. Read with Utilities retirement plans → · Plans in Wisconsin →

Alliant Energy Corporation 401(k) Savings Plan in the asset neighbourhood

Alliant Energy Corporation 401(k) Savings PlanAlliant Energy Corporation 4…$1.4BAvaya Savings Plan for Salaried EmployeesAvaya Savings Plan for Salar…$1.4BRr Donnelley Savings Plan$1.4BJ.B. Hunt Transport Services, Inc. Employee Retirement PlanJ.B. Hunt Transport Services…$1.4BBaystate Health, Inc Retirement PlanBaystate Health, Inc Retirem…$1.4B
End-of-year total assets ($B) among Alliant Energy Corporation 401(k) Savings Plan and nearest nationwide 401(k) peers. Source: DOL Form 5500 plan year 2024.

Wisconsin filing particulars

Total Assets (Beginning of Year)$1.3B
Net Assets (End of Year)$1.4B
Net Income$88M
Employer EIN391914946
Plan Effective Date1983-01-01
Filing StatusFILING RECEIVED

Sponsor Plan History (Alliant Energy Corporate Services, Inc.)

Sponsor-wide plan assets over time

All Alliant Energy Corporate Services, Inc. plans reported in each filing year

Latest sponsor-wide plan assets
$1.6B 16.956327726571477% vs 2022
2024 filing year
$1.3B$1.4B$1.5B$1.6B$1.7B 202220232024 $1.4B $1.63B ▲ +16.4%
Year Plans Participants Total Assets
2022 2 3,712 $1.4B
2023 2 3,484 $1.6B
2024 2 3,621 $1.6B

Nearby 401(k) Plans in Wisconsin

Peer 401(k) plans, same state, same plan type, ranked by total assets.

Alliant Energy Corporation 401(k) Savings Plan vs. nearby 401(k) plans in Wisconsin, assets vs. participants Scatter plot of 6 data points. -20000020000400006000080000100000 024681012 Total assets ($B) Participants Alliant Energy Corporation 401(k) Savings Plan, Total assets ($B): 1.409016019 · Participants: 3265Alliant Energy Corporation 401(k) Savings PlanAdvocate Aurora Health 401(k) Plan, Total assets ($B): 10.487791739 · Participants: 80015Advocate Aurora Health 401(k) PlanJohnson Controls Retirement Savings and Investment Plan, Total assets ($B): 7.188548319 · Participants: 28489Johnson Controls Retirement Savings and Investment PlanFiserv 401(k) Savings Plan, Total assets ($B): 5.136404794 · Participants: 26372Fiserv 401(k) Savings PlanKimberly-Clark Corporation 401(k) & Profit Sharing Plan, Total assets ($B): 4.988151 · Participants: 11661Kimberly-Clark Corporation 401(k) & Profit Sharing PlanRockwell Automation Retirement Savings Plan, Total assets ($B): 3.765132976 · Participants: 9217Rockwell Automation Retirement Savings Plan
Alliant Energy Corporation 401(k) Savings Plan vs. nearby 401(k) plans in Wisconsin, assets vs. participants
Compare Alliant Energy Corporation 401(k) Savings Plan side-by-side with 3 peers →

Alliant Energy Corporation 401(k) Savings Plan's out-of-state 401(k) peers by assets and headcount

Outside Wisconsin, the nearest 401(k) by assets is Avaya Savings Plan for Salaried Employees in NJ ($1.4B); by covered participants it is Iqor Retirement Savings Plan in FL (3,265 participants). Same-state nearby plans are listed separately above.

Closest by plan assets

Nearest other-state filings by tot_assets_eoy ($1.4B here).

Similar participant headcount

Nearest other-state filings by covered participants (3,265 participants); asset peers above are excluded.

DOL Form 5500 plan year 2024. Asset totals can differ widely at the same headcount; neither axis is a quality rating.

Frequently Asked Questions

How did Alliant Energy Corporation 401(k) Savings Plan assets move in 2024? ▼
Alliant Energy Corporation 401(k) Savings Plan grew at a solid clip - up 6.6% during 2024, from $1.3B to $1.4B. Reported net income was $88M.
How have Alliant Energy Corporate Services, Inc. plan assets changed over time? ▼
Across 3 plan years on file (2022-2024), Alliant Energy Corporate Services, Inc.'s sponsor-wide assets grew 17.0%, from $1.4B to $1.6B.
Where does Alliant Energy Corporation 401(k) Savings Plan rank by assets among Form 5500 filers? ▼
Alliant Energy Corporation 401(k) Savings Plan ranks in the 99th percentile by end-of-year assets among 123,622 plans that reported assets for plan year 2024 (among the largest 1% of all filed plans).
Which 401(k) plans are similar in size to Alliant Energy Corporation 401(k) Savings Plan? ▼
Among 401(k) plans in other states, the closest by assets is Avaya Savings Plan for Salaried Employees in NJ ($1.4B, 1,459 participants).
Which 401(k) plans cover a similar participant headcount to Alliant Energy Corporation 401(k) Savings Plan? ▼
Among 401(k) plans in other states, the closest by covered participants is Iqor Retirement Savings Plan in FL (3,265 participants, $49M in assets).

Source: U.S. Department of Labor, Employee Benefits Security Administration (EBSA), Form 5500 public disclosure dataset. Plan year 2024.

Source: DOL EFAST2 filing system (efast.dol.gov) - original filing retrieval by EIN 391914946.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from U.S. Department of Labor Form 5500 filings (EBSA). See our methodology for details.