401(k) · DOL Form 5500 · 2024

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

Data updated 2026-08-11

$1.4B
Total assets: 3,265
Participants: 99th
Percentile by assets: $431,552
Avg per participant

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.

99th percentile by assets (of 123,622 plans)
#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.

$1.4B
total plan assets (2024 EOY): 3,265
covered participants: 99th
percentile by assets (of 123,622 plans): $431,552
avg assets per participant

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 →

State

Wisconsin

Industry

Utilities

Participants vs Wisconsin filers

In Wisconsin, the average filing covers about 563 participants across 2,940 plans. Alliant Energy Corporation 401(k) Savings Plan reports 3,265 participants - 5.8x that state average ($1.4B EOY assets).

Wisconsin filing particulars

Total Assets (Beginning of Year)	$1.3B
Net Assets (End of Year)	$1.4B
Net Income	$88M
Employer EIN	391914946
Plan Effective Date	1983-01-01
Filing Status	FILING RECEIVED

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

Total plan assets by year, all Alliant Energy Corporate Services, Inc. plans on file

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

Advocate Aurora Health 401(k) Plan $10.5B · 80,015
Johnson Controls Retirement Savings and Investment Plan $7.2B · 28,489
Fiserv 401(k) Savings Plan $5.1B · 26,372
Kimberly-Clark Corporation 401(k) & Profit Sharing Plan $5.0B · 11,661
Rockwell Automation Retirement Savings Plan $3.8B · 9,217

Compare Alliant Energy Corporation 401(k) Saving… side-by-side with 3 peers →

Similar-Sized 401(k) Plans Nationally

401(k) plans in other states closest to Alliant Energy Corporation 401(k) Savings Plan by total assets, not by location.

Avaya Savings Plan for Salaried Employees (NJ) $1.4B · 1,459
Rr Donnelley Savings Plan (IL) $1.4B · 11,649
J.B. Hunt Transport Services, Inc. Employee Retirement Plan (AR) $1.4B · 35,023
Baystate Health, Inc Retirement Plan (MA) $1.4B · 13,531

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).

Next read for Alliant Energy Corporation 401(k) Saving…

Filing takeaways

Ways to act on Alliant Energy Corporation 401(k) Savings Plan's numbers.

By total assets, Alliant Energy Corporation 401(k) Savings Plan ranks among the largest 1% of all filed plans. See the largest plans
Compare it side-by-side against 3 similar 401(k) plans in Wisconsin. Compare plans
Alliant Energy Corporate Services, Inc.'s sponsor-wide assets have grown 17.0% since 2022 across 3 plan years on file. More Utilities plans

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.