Alliant Energy Corporate Services 401(k) and pension plans

Alliant Energy Corporate Services, Inc., Madison, WI. EIN 39-1914946. Annual reports 2009–2024. Also filed as Alliant Energy Corporate Services, Inc; Alliant Energy Corporate Services; Alliant Energy Corporate Services Inc.

Alliant Energy Corporate Services, Inc. has 2 active retirement plans on file. The largest is the Alliant Energy Corporation 401(k) Savings Plan, with 4,222 participants and $1.4 billion in assets in 2024. Empower has been its recordkeeper since 2015.

Active plans: 2
Participants: 6,378
Plan assets: $1.6 billion
401(k) recordkeeper: Empower
Plans on file: 3
Industry: Utilities

All 3 plans

Active plans first

Alliant Energy Corporation 401(k) Savings Plan

401(k) with ESOPActive

Active. The plan filed its annual report for the 2024 plan year.

Plan number: 005Employer EIN 39-1914946
Participants (2024): 4,222
Net assets (2024): $1.4 billion
Recordkeeper: EmpowerEarlier: J.P. Morgan (2009–2014)
Plan administrator: Benefit Plans Committee of Alliant Energy Corporation
4902 North Biltmore Lane
Madison, WI 53718
(608) 458-3311As filed for 2024
In effect since: January 1, 1983

Plans merged into this one: Ies Employee Stock Ownership Plan (2011).

Year by year, 2009 to 2024

Plan year	Participants	Net assets	Recordkeeper
2024	4,222	$1.4 billion	Empower
2023	4,517	$1.3 billion	Empower
2022	4,430	$1.2 billion	Empower
2021	4,522	$1.5 billion	Empower
2020	4,586	$1.4 billion	Empower
2019	4,711	$1.2 billion	Empower
2018	4,900	$1.0 billion	Empower
2017	4,979	$1.1 billion	Empower
2016	4,923	$967 million	Empower
2015	5,155	$909 million	Empower
2014	5,162	$925 million	J.P. Morgan
2013	4,904	$863 million	J.P. Morgan
2012	4,858	$728 million	J.P. Morgan
2011	4,949	$658 million	J.P. Morgan
2010	5,074	$665 million	J.P. Morgan
2009	5,211	$582 million	J.P. Morgan

Alliant Energy Cash Balance Pension Plan

Cash balance pensionActive

Active. The plan filed its annual report for the 2024 plan year.

Plan number: 001Employer EIN 39-1914946
Participants (2024): 2,156
Net assets (2024): $226 million
Plan administrator: Alliant Energy Corporate Services Inc
4902 N. Biltmore Lane, Suite 1000
Madison, WI 53718
(608) 458-3311As filed for 2024
In effect since: April 1, 1940

Year by year, 2009 to 2024

Plan year	Participants	Net assets	Recordkeeper
2024	2,156	$226 million	not listed
2023	2,228	$232 million	not listed
2022	2,299	$232 million	not listed
2021	2,390	$327 million	not listed
2020	2,498	$327 million	not listed
2019	2,607	$310 million	not listed
2018	2,744	$276 million	not listed
2017	2,856	$324 million	not listed
2016	2,952	$307 million	not listed
2015	3,047	$316 million	not listed
2014	3,284	$360 million	not listed
2013	3,323	$363 million	not listed
2012	3,397	$351 million	not listed
2011	3,482	$331 million	not listed
2010	3,585	$342 million	not listed
2009	3,670	$317 million	not listed

Ies Employee Stock Ownership Plan

Employee stock ownership plan (ESOP)Merged

Merged. In 2011 its assets moved to the Alliant Energy Corp 401(k) Savings, sponsored by Alliant Energy Corporate Services, Inc. (EIN 39-1914946, plan 005). Accounts moved with them, so that plan is the one to contact.

Plan number: 008Employer EIN 39-1914946
Participants (2010): 163
Net assets (2010): $2.1 million
Plan administrator: Alliant Energy Corporate Services, Inc
4902 N Biltmore Lane, Suite 1000
Madison, WI 53718
(608) 458-3311As filed for 2011
In effect since: December 31, 1975

Year by year, 2009 to 2011

Plan year	Participants	Net assets	Recordkeeper
2011	0	n/a	not listed
2010	163	$2.1 million	not listed
2009	166	$1.7 million	not listed

If you had money in one of these plans

Call Empower (empower.com), which runs the Alliant Energy Corporation 401(k) Savings Plan. With your Social Security number and the plan name, it can tell you whether you still have a balance and, if not, where it went.
Or call the plan administrator listed on the plan below ((608) 458-3311). That number was filed for 2024; ask for the benefits or retirement plan office.
If your plan was merged, your account moved with it. Follow the link on the plan to the plan it went into, and contact that one.
Still stuck? The Department of Labor's benefits advisers help for free: askebsa.dol.gov or 1-866-444-3272. Never pay anyone to find your own money.

What these numbers are

They come from the Form 5500 annual reports each plan files with the Department of Labor, as the plan filed them. A plan year is usually a calendar year.
Participants counts everyone in the plan at year end: current employees, former employees who still have a balance or a pension coming, and retirees or beneficiaries being paid.
The recordkeeper is the service provider whose Schedule C entry says it keeps the plan's records. Small plans do not file Schedule C, so some plans show none.
We cannot see anyone's account. Only the plan or its recordkeeper can tell you your balance.

Sources: U.S. Department of Labor, Form 5500 datasets and PBGC trusteed plans. How we read them.