401(k) · DOL Form 5500 · 2023

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

Data updated 2026-08-25

$1.3B
Total assets Very large vs avg
3,101
Participants Above avg headcount
99th
Percentile by assets National rank
$426,049
Avg per participant High balance/head
PlainRetire home → About this data RSS: change history

Official DOL plan name: Alliant Energy Corporation 401(k) Savings Plan · Sponsored by Alliant Energy Corporate Services, Inc. · Wisconsin · Utilities

$1.3B in assets, 3,101 participants

Alliant Energy Corporate Services, Inc.'s Alliant Energy Corporation 401(k) Savings Plan reported $1.3B in total assets and 3,101 participants in its 2023 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.

  • #660 in Utilities (721 peers)

Coverage in Wisconsin

Alliant Energy Corporation 401(k) Savings Plan covers 3,101 participants in Wisconsin, 5.5x the typical Wisconsin plan (state average ~563 per filing). Assets: $1.3B.

#660
in Utilities (721 peers)
+13.3%
assets growth YoY
13×
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 2023 · DOL Form 5500

$1,321,177,371 Top 1% higher than 99% of 127,068 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 2023

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

Plan-year 2023 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 (3,101 participants).

What changed between DOL Form 5500 filings

plan year 2022 → plan year 2023

  • Alliant Energy Corporation 401(k) Savings Plan reported net income rose from -$347M in the plan year 2022 filing to $155M in the plan year 2023 filing.
  • Alliant Energy Corporation 401(k) Savings Plan end-of-year assets rose from $1.2B in the plan year 2022 filing to $1.3B in the plan year 2023 filing.
  • Alliant Energy Corporation 401(k) Savings Plan reported participants fell from 3,263 in the plan year 2022 filing to 3,101 in the plan year 2023 filing.

See the national 2022→2023 release diff →

Published 5500 schedule card

Filing strip 391914946 · Alliant Energy Corporate Services, Inc. PY 2023 · 401(k)

Alliant Energy Corporation 401(k) Savings Plan · $1.3B · 3,101 · 99th

  • ASSETS $1.3B
  • ASSETS 3,101
  • ASSETS 99th
  • ASSETS 401(k)
  • ASSETS near Novelis Savings and Retirement Plan
  • ASSETS ind #660

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…$1.3BNovelis Savings and Retirement PlanNovelis Savings and Retireme…$1.3BHub International Limited 401(k) Savings PlanHub International Limited 40…$1.3BWabtec Savings Plan$1.3BClayton Homes, Inc. 401(k) Retirement PlanClayton Homes, Inc. 401(k) R…$1.3B
End-of-year total assets ($B) among Alliant Energy Corporation 401(k) Savings Plan and nearest nationwide 401(k) peers. Source: DOL Form 5500 plan year 2023.

Wisconsin filing particulars

Total Assets (Beginning of Year)$1.2B
Net Assets (End of Year)$1.3B
Net Income$155M
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 0246810 Total assets ($B) Participants Alliant Energy Corporation 401(k) Savings Plan, Total assets ($B): 1.321177371 · Participants: 3101Alliant Energy Corporation 401(k) Savings PlanAdvocate Aurora Health 401(k) Plan, Total assets ($B): 9.125723544 · Participants: 76956Advocate Aurora Health 401(k) PlanJohnson Controls Retirement Savings and Investment Plan, Total assets ($B): 6.160116767 · Participants: 28904Johnson Controls Retirement Savings and Investment PlanFiserv 401(k) Savings Plan, Total assets ($B): 4.81171463 · Participants: 25280Fiserv 401(k) Savings PlanKimberly-Clark Corporation 401(k) & Profit Sharing Plan, Total assets ($B): 4.550761 · Participants: 11236Kimberly-Clark Corporation 401(k) & Profit Sharing PlanRockwell Automation Retirement Savings Plan, Total assets ($B): 3.62235882 · Participants: 8877Rockwell 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 Novelis Savings and Retirement Plan in GA ($1.3B); by covered participants it is Social Finance, Inc. 401(k) Plan in CA (3,101 participants). Same-state nearby plans are listed separately above.

Closest by plan assets

Nearest other-state filings by tot_assets_eoy ($1.3B here).

Similar participant headcount

Nearest other-state filings by covered participants (3,101 participants); asset peers above are excluded.

DOL Form 5500 plan year 2023. 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 2023? ▼
Alliant Energy Corporation 401(k) Savings Plan grew at a solid clip - up 13.3% during 2023, from $1.2B to $1.3B. Reported net income was $155M.
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 127,072 plans that reported assets for plan year 2023 (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 Novelis Savings and Retirement Plan in GA ($1.3B, 5,439 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 Social Finance, Inc. 401(k) Plan in CA (3,101 participants, $140M in assets).

Source: U.S. Department of Labor, Employee Benefits Security Administration (EBSA), Form 5500 public disclosure dataset. Plan year 2023.

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.