Employer · plans filed under one EIN
Alliant Energy Corporate Services, Inc.
Madison, WI · Utilities
Form 5500 information is as filed by the plan administrator with the Department of Labor and may be amended. Figures reflect the plan year shown, not current balances.
Alliant Energy Corporate Services, Inc., based in Madison, Wisconsin, sponsors 2 retirement plans with 100 or more participants: 1 defined contribution and 1 defined benefit. Together they reported 6,378 participant records and $1.63B in net assets.
The largest is Alliant Energy Corporation 401(k) Savings Plan, an ESOP with a 401(k) feature with 4,222 participants. A person can be counted in more than one plan, so the participant total is a count of records rather than of people.
Employer contributions across the plans were $36.6M and participant contributions $45.0M in the latest plan years; benefits paid were $214M. Schedule C compensation reported to service provider organisations totalled $1.6M.
Combined net assets moved from $899M in 2009 to $1.63B in 2024 (up 82%). Plan mergers and spin-offs show up here as steps in the series.
Plans
| Plan | Kind | Plan year | Participants | Net assets | Per participant | Employer / active | Sch. C compensation |
|---|---|---|---|---|---|---|---|
| Alliant Energy Corporation 401(k) Savings Plan | ESOP with a 401(k) feature | 2024 | 4,222 | $1.41B | $333,732 | $10,411 | $962K |
| Alliant Energy Cash Balance Pension Plan | cash balance pension plan | 2024 | 2,156 | $226M | $104,642 | $20,040 | $683K |
| US median, plan year 2024: DC plans $53,102 per participant, $2,175 employer contribution per active participant; DB plans $86,221 and $10,244. | |||||||
Trend by plan year
| Plan year | Plans | Participant records | Net assets | Employer contributions | Participant contributions |
|---|---|---|---|---|---|
| 2024 | 2 | 6,378 | $1.63B | $36.6M | $45.0M |
| 2023 | 2 | 6,745 | $1.55B | $29.0M | $42.5M |
| 2022 | 2 | 6,729 | $1.40B | $27.6M | $41.5M |
| 2021 | 2 | 6,912 | $1.84B | $26.3M | $41.2M |
| 2020 | 2 | 7,084 | $1.72B | $36.8M | $40.5M |
| 2019 | 2 | 7,318 | $1.55B | $29.9M | $39.6M |
| 2018 | 2 | 7,644 | $1.31B | $25.1M | $38.6M |
| 2017 | 2 | 7,835 | $1.45B | $25.0M | $38.7M |
| 2016 | 2 | 7,875 | $1.27B | $23.5M | $36.7M |
| 2015 | 2 | 8,202 | $1.22B | $25.7M | $37.1M |
| 2014 | 2 | 8,446 | $1.29B | $23.6M | $33.8M |
| 2013 | 2 | 8,227 | $1.23B | $19.2M | $30.8M |
| 2012 | 2 | 8,255 | $1.08B | $18.6M | $29.1M |
| 2011 | 2 | 8,431 | $990M | $30.0M | $29.2M |
| 2010 | 2 | 8,659 | $1.01B | $26.9M | $27.3M |
| 2009 | 2 | 8,881 | $899M | $36.0M | $26.9M |
History of the plans listed above, in the years each filed the full Form 5500 with 100 or more participants. Plans that have since terminated are not included.
Service providers
| Organisation | Services reported | Plans | Compensation reported |
|---|---|---|---|
| Empower Advisory Group, LLC | Investment management | 1 | $611,240 |
| Willis Towers Watson US LLC | Actuarial; Plan Administrator | 1 | $294,948 |
| Empower Annuity Ins Co. of America | Recordkeeping and information management | 1 | $291,753 |
| Aon Investment USA, Inc. | Investment management; Investment advisory (plan) | 1 | $140,150 |
| Principal Custody Solutions | Trustee (bank, trust company, or similar financial institution) | 1 | $82,250 |
| Aberdeen Emerging Markets Equity Fu | Investment management | 1 | $44,917 |
| Morgan Stanley Investment Mgmt. | Investment management | 1 | $39,282 |
| Fidelity Investments Inst Co., LLC | Participant loan processing | 1 | $37,145 |
| Parametric Portfolio Associates | Investment management | 1 | $29,481 |
| Lgima Long Duration US Credit Fund | Investment management | 1 | $22,522 |
| Strategic Advisors, Inc. | Investment advisory (plan) | 1 | $22,171 |
| Nisa Investment Advisors LLC | Investment management | 1 | $15,497 |
| Coleman & Williams, Ltd. | Accounting (including auditing) | 1 | $13,785 |
| Charles Schwab & Co., Inc. | — | 1 | $180 |
Organisations paid $5,000 or more by any of these plans, from Schedule C. Individuals are not shown.
Questions and answers
How many retirement plans does Alliant Energy Corporate Services, Inc. have?
2 plans with 100 or more participants filed Form 5500 under its employer identification number for the latest plan years: Alliant Energy Corporation 401(k) Savings Plan and Alliant Energy Cash Balance Pension Plan. Smaller plans and plans filed under a subsidiary's number are not grouped here.
How much does Alliant Energy Corporate Services, Inc. contribute to its plans?
$36,568,640 in employer contributions across these plans in their latest plan years, about $11,217 per active participant record. Form 5500 reports totals and not the match or accrual formula.
Who provides services to these plans?
Schedule C filings name Empower Advisory Group, LLC, Willis Towers Watson US LLC, Empower Annuity Ins Co. of America and Aon Investment USA, Inc. and others. Only organisations paid $5,000 or more by a plan are listed on Schedule C.
Where does this come from?
Form 5500 annual reports filed with the Department of Labor's EFAST2 system, from the EBSA research files, with filings received through 24 Aug 2026. Figures are as filed and may be amended.
Provenance
Source: U.S. Department of Labor, Employee Benefits Security Administration, Form 5500 research files, public domain, with filings received through 24 Aug 2026. Plans are grouped by the sponsor's employer identification number exactly as filed; a company that files under several EINs appears as several employers. See the methodology and corrections.