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IRS-authorized e-file provider · not the IRS

Nonprofit · EIN 94-3274043

CALIFORNIA INDEPENDENT SYSTEM OPERATOR CORPORATION

Also known as CALIFORNIA ISO

Tax-exempt · FOLSOM, CA 95630

What it must file and when

IRS records say it files Form 990 or 990-EZ. Based on its last return; a smaller organization may file the 990-N. Its accounting year ends in December, so each return is due on the 15th day of the 5th month after that.

Tax yearYear endedDueIRS public records
2025December 31, 2025May 15, 2026Not on file
2024December 31, 2024May 15, 2025990 on file
2023December 31, 2023May 15, 2024990 on file

File the 2025 990-EZ for CALIFORNIA INDEPENDENT SYSTEM OPERATOR CORPORATION

Due May 15, 2026 · e-filed with the IRS by 990.tax, an IRS-authorized e-file provider

IRS record

EIN
94-3274043
Tax-exempt status
501(c)(3): Charitable, religious, educational or scientific organization
Foundation status
Supporting organization (509(a)(3))
Donations deductible (Pub 78)
Supporting organization of unknown type
Exempt since
1998
Accounting year ends
December
Files
Form 990 or 990-EZ

Filing history

FormYear endedRevenueExpensesAssets
990December 2024–––
990December 2023$272,540,764$277,699,154$1,459,997,265
990December 2022$255,713,716$250,885,967$1,587,900,049
990December 2021–––
990TDecember 2021–––
990December 2020–––
990TDecember 2020–––
990December 2018–––
990December 2017–––

990-N: the IRS publishes only the latest e-Postcard per organization; earlier years appear here as 990.tax collects the monthly files. 990, 990-EZ, 990-PF: e-filed returns processed since 2019; amounts from the IRS Statistics of Income extracts where available.

Other organizations in FOLSOM