v3.26.1
Related Party Transactions
 6 Months Ended
Jun. 30, 2026
Related Party Transactions [Abstract]  
RELATED PARTY TRANSACTIONS RELATED-PARTY TRANSACTIONS
In the ordinary course of business, Ameren Missouri and Ameren Illinois have engaged in, and may in the future engage in, affiliate transactions. These transactions primarily consist of natural gas and power purchases and sales, services received or rendered, and borrowings and lendings. Transactions between Ameren’s subsidiaries are reported as affiliate transactions on their individual financial statements, but those transactions are eliminated in consolidation for Ameren’s consolidated financial statements. For a discussion of material related-party agreements and money pool agreements, see Note 13 – Related-party Transactions and Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of the Form 10-K.
Support Services Agreements
Ameren Missouri and Ameren Illinois had long-term receivables included in “Other assets” from Ameren Services of $33 million and $35 million, respectively, as of June 30, 2026, and $36 million and $38 million, respectively, as of December 31, 2025, related to Ameren Services’ allocated portion of Ameren’s pension and postretirement benefit plans.
Tax Allocation Agreement
See Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of the Form 10-K for a discussion of the tax allocation agreement. The following table presents the affiliate balances related to income taxes for Ameren Missouri and Ameren Illinois as of June 30, 2026, and December 31, 2025:
June 30, 2026December 31, 2025
Ameren MissouriAmeren IllinoisAmeren MissouriAmeren Illinois
Income taxes payable to parent(a)
$38$10$—$4
Income taxes receivable from parent(b)
——37
(a)Included in “Accounts payable – affiliates” on the balance sheet.
(b)Included in “Accounts receivable – affiliates” on the balance sheet.
Effects of Related-party Transactions on the Statement of Income
The following table presents the impact on Ameren Missouri and Ameren Illinois of related-party transactions for the three and six months ended June 30, 2026 and 2025:
Three MonthsSix Months
AgreementIncome Statement
Line Item		Ameren
Missouri		Ameren
Illinois		Ameren
Missouri		Ameren
Illinois
Ameren Missouri and Ameren IllinoisOperating Revenues2026$11 $(a)$21 $(a)
rent and facility services
20258 1 15 1 
Ameren Illinois interconnection agreementOperating Revenues2026(b)(a)(b)(a)
with Ameren Missouri2025(b)(a)(b)(a)
Ameren Missouri and Ameren Illinois miscellaneousOperating Revenues2026$2 $1 $2 $1 
support services2025(a)3 (a)5 
Total Operating Revenues2026$13 $1 $23 $1 
20258 4 15 6 
Ameren Missouri and Ameren IllinoisPurchased Power2026$3 $1 $5 $2 
transmission services from ATXI20252 1 5 1 
Ameren Missouri interconnection agreementPurchased Power2026(a)(b)(a)(b)
with Ameren Illinois2025(a)(b)(a)(b)
Total Purchased Power2026$3 $1 $5 $2 
20252 1 5 1 
Ameren Missouri and Ameren IllinoisOther Operations and Maintenance2026$(a)$(a)$(a)$(a)
rent and facility services
2025(a)2 (a)3 
Ameren Services support servicesOther Operations and Maintenance2026$48 $46 $96 $90 
agreement
202544 40 88 80 
Total Other Operations and2026$48 $46 $96 $76 
Maintenance202544 42 88 83 
Money pool interest (advances)(Interest Charges)/Other Income, Net2026$(a)$(a)$(a)$(a)
2025(a)(a)(a)(a)
Long-term debt, net - related parties(Interest Charges)2026$(1)$(a)$(2)$(a)
2025(1)(a)(1)(a)
(a)Amount less than $1 million.
(b)Not applicable.