The chronology. December 18, 2025, FERC issued a separate order (not yesterday's) directing PJM specifically to revise its tariff to provide clear rates, terms, and conditions for co-located load (a data center plus its own on-site generation, sitting at the same point on the grid) and behind-the-meter generation. That was a Section 206 finding against PJM's co-location tariff, but it gave PJM a direct path to do the Section 205 compliance filing itself. February 23, 2026: PJM filed its compliance package with FERC, with a requested July 31, 2026 effective date. That filing is currently under review. June 18, 2026: FERC's broader show-cause order to all six RTOs (yesterday's news) covers large-load interconnection more generally, of which co-location is a subset. PJM is the only RTO that is already actively filing Section 205 tariff revisions on the overlapping subject matter. The structural implication: PJM can credibly file an abeyance request by August 2 saying 'we are already mid-flight on a Section 205 compliance filing addressing a substantial overlap with the issues identified in your show-cause order, please hold the show-cause in abeyance pending the outcome of that compliance filing.' The other five RTOs (MISO, SPP, CAISO, ISO-NE, NYISO) do not have an equivalent in-flight filing to point to and would have to build one from scratch inside 45 days. For scope context, PJM is the largest grid operator in the country by load and the biggest data center load in the country sits inside PJM (Northern Virginia / data center alley). So the RTO with the most data center load is also the only one with a credible abeyance path.
Primary source · Gibson Dunn — analysis of Dec 18, 2025 FERC order to PJM ↗
Why it matters
Two near-term consequences. (1) PJM is the most-watched docket of all six for the next six weeks — and probably the only one where the substantive tariff debate happens through a Section 205 process rather than a Section 206 process. That changes who participates and who has the burden of proof, which means the regulatory filings that will end up shaping data-center cost allocation in PJM look more like industry-driven tariff design than FERC-driven enforcement. The corpus has to track those filings differently than it would the other five. (2) The July 31 effective date PJM requested back in February is now the de facto reference deadline for the federal cost-allocation answer in the largest data center market in the country — which is two and a half weeks before the August 17 default show-cause deadline. A developer trying to forecast cost-allocation exposure for a Northern Virginia / PJM site should plan to know the answer by August 1, not August 17.
Related filings
FERC show cause orders Jun 18 / Section 206 / PJM MISO SPP CAISO ISO-NE NYISO / 30-day informational report Jul 20 / 60-day tariff response Aug 17 / 90-day abeyance request Aug 3 / five reform categories / cost-shift prevention is the big one / colocation + BTMG rules / flexible-load transmission services
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