August 17, 2026 is the FERC filing wall for the six large-load show-cause dockets the Commission opened on June 18. Every RTO and ISO that did not seek a stay by August 3 has to put a full Section 206 answer, or a voluntary Section 205 tariff reform package, on the docket by that date. The six dockets are EL26-67 for PJM, EL26-70 for MISO, EL26-68 for SPP, EL26-71 for CAISO, EL26-72 for ISO-NE, and EL26-69 for NYISO. Stakeholder comments are due September 16, and the abeyance cap is 90 days with no signal of reflexive extension.
The August 5 news read walked through the docket itself. What is coming into view now, with ten days to run, is the shape of the split. The RTOs that file voluntary Section 205 reforms are writing the rulebook. The RTOs that only answer under Section 206 accept a Commission-imposed rulebook. The gap between those two postures is where the near-term interconnection-revenue pull sits for hyperscaler siting decisions in the fall.
The five reform areas, in order of near-term dollar impact
The Commission flagged five reform focus areas in the show-cause orders. In the order that they carry near-term interconnection revenue for the RTO’s transmission owners, they read as follows.
First, application and study processes for large-load transmission service. This is the front door for any 50 MW or greater customer at 69 kV or higher, and the reform-side proposals are expected to include expedited-study lanes for pre-vetted load categories (data centers with defined ramp curves, industrial hydrogen facilities with defined offtake profiles), tighter deposit-and-milestone structures to filter speculative queue positions, and a fast-track re-study path for existing generation-side cluster study interactions. Whichever RTO writes the cleanest application-side reform pulls the next round of large-load applications toward its footprint.
Second, cost transparency and cost-shift protections for existing customers. The existing-customer cost-shift is the political flashpoint that surfaces in every state PUC filing when a hyperscaler siting decision hits the news, and the Commission is signaling that the RTOs need to put a defensible cost-allocation methodology on paper. The reform-side proposals here include causer-pays formulas for network upgrades tied to large loads, explicit revenue-requirement tests for the incremental capex, and standardized cost-allocation exhibits that state commissions can lift directly into their retail-rate proceedings. RTOs that write a defensible cost-shift protection package remove the state-level friction that has been slowing 2026 hyperscaler PPAs.
Third, co-location arrangement rates and conditions, including behind-the-meter carve-outs. This is the piece most directly wired into the nuclear-plus-data-center pipeline. The March 2026 Commission decision on Talen-Amazon at Susquehanna carved a narrow window for behind-the-meter co-location, and the reform-side proposals in PJM and MISO especially will test how wide that window can open. The proposals expected on the docket include standardized co-location tariff sheets with pre-defined backup service terms, cost-of-service methodologies for the incremental transmission use, and eligibility criteria that distinguish true behind-the-meter arrangements from grid-supported co-location. The Kairos-TVA-Google, Aalo-Crusoe, and the microreactor preorder book all price differently depending on how these tariffs land.
Fourth, flexible large loads and behind-the-meter generation services. The reform-side proposals here include curtailable-load tariffs with defined compensation for large loads that agree to shed capacity during scarcity events, standardized behind-the-meter generation service terms for on-site gas or nuclear paired with grid backup, and firm-capacity treatment for behind-the-meter resources that meet defined performance criteria. The flexible-load side is what unlocks a class of interconnection paths that are otherwise stuck behind cluster study timelines, and the RTOs with the deepest flexibility carve-outs collect the load faster.
Fifth, electrically proximate large load interconnection terms. This is the closest-to-generation category, covering large loads sited near existing or planned generation resources. The reform-side proposals include streamlined interconnection paths for loads within a defined electrical proximity of a generator, cost-allocation methodologies for shared network upgrades, and integrated study protocols that avoid double-counting between the generator-side and load-side queues. This is the category where the ERCOT batch-zero learnings from the July filing cycle transfer most directly, even though ERCOT is not one of the six FERC dockets.
The six RTOs, in order of expected filing posture
The Section 205 versus Section 206 posture split is not going to be uniform. Reading the docket record and the state-level tariff filings from the past six months, the six filings sort into three groups by expected posture.
Lead group: RTOs expected to file substantive Section 205 reforms.
PJM (EL26-67) is the RTO with the largest pipeline of pending large-load applications and the most acute cost-shift exposure. The 2026 capacity auction outcomes and the Susquehanna decision put PJM in a position where it has to write the rulebook rather than answer under Section 206. Expect a full Section 205 package covering all five focus areas, with the co-location and flexible-load sheets carrying the most detailed proposals. PJM’s filing is the one the other RTOs will read first.
MISO (EL26-70) has an active DER interconnection reform track and has been building a case for a large-load-specific study process through its stakeholder committees in 2026. Expect a Section 205 filing that leans hardest on the application and study process side, with cost-shift protections tied to the existing MISO cost-allocation framework. The co-location piece is less developed on the MISO side and may come in as a Section 206 answer within the same brief.
Middle group: RTOs expected to file mixed Section 205 and Section 206 packages.
SPP (EL26-68) has the smallest large-load pipeline of the six but a very active generation-side cluster study process. The reform posture here is likely a partial Section 205 filing on the application side, paired with Section 206 answers on the co-location and flexible-load sides where SPP has less developed precedent. The August 17 filing is more likely to be a scoping document that commits to a fuller Section 205 filing later in the docket than a complete reform package on the wall.
CAISO (EL26-71) has the most complex existing tariff structure of the six and the most active state-level parallel proceedings (California PUC and CEC). Expect a Section 205 filing that leans on the co-location and behind-the-meter piece, tied to the state-level microgrid and behind-the-meter generation rulebooks, with Section 206 answers on the application-side reforms where CAISO has less standalone latitude. The CAISO filing is the one to read for how state-level and FERC-level jurisdiction interact.
Trailing group: RTOs expected to file primarily Section 206 answers.
ISO-NE (EL26-72) has a small large-load pipeline and a highly contested transmission cost-allocation history. Expect a Section 206 answer that defends the existing tariff on cost-shift grounds and proposes limited reforms on the application-side, with the co-location and flexible-load pieces deferred to a subsequent filing cycle.
NYISO (EL26-69) is in a similar posture. The NYISO tariff has active state-level parallel proceedings (New York PSC), and the FERC filing is likely to defer substantive co-location and flexible-load reforms to the state-level track. Expect a Section 206 answer on August 17 with a commitment to a Section 205 filing later in the docket.
What the split tells the market
The two lead-group RTOs (PJM and MISO) filing substantive Section 205 packages pulls the hyperscaler siting decisions inside those footprints toward standardized tariff arrangements. That is the piece that removes the largest current source of friction in 2026 large-load PPAs: the one-off nature of every co-location and behind-the-meter arrangement, which forces each transaction into bespoke tariff negotiation.
The middle-group RTOs (SPP and CAISO) filing mixed packages sets up a second wave of Section 205 filings later in the docket, and the interconnection-revenue pull inside those footprints lags PJM and MISO by roughly a filing cycle.
The trailing-group RTOs (ISO-NE and NYISO) filing primarily Section 206 answers cedes the near-term rulebook to Commission-imposed remedies, and the hyperscaler siting decisions inside those footprints continue to require bespoke tariff negotiation. That is a competitive disadvantage against PJM and MISO for the next twelve to eighteen months of siting decisions.
For transmission-owner equity inside PJM and MISO, the August 17 filing is a positive catalyst if the Section 205 package is substantive. The load-serving-entity side inside those footprints has to absorb the cost-shift protections, which is a modest headwind but one that the Commission has been signaling clearly enough that the 2026 estimates have already been reset in most sell-side models.
What to watch through August 17
Three things.
One, whether PJM’s Section 205 filing includes a standardized co-location tariff sheet with defined backup service terms, or whether it defers the co-location piece to a subsequent filing cycle. A standardized co-location tariff sheet on August 17 is the single most consequential piece of paper in the docket, because it sets the template the other RTOs read from.
Two, whether MISO’s filing includes a large-load-specific study process that carves large loads out of the existing DER interconnection queue. A carved-out study process removes the queue interaction that has been slowing large-load applications inside the MISO footprint, and it commits MISO to writing the same rulebook PJM is writing.
Three, whether any of the trailing-group RTOs (ISO-NE, NYISO) surprise on the upside with a Section 205 filing that was not signaled in the state-level parallel proceedings. A surprise Section 205 filing from either of them shifts the competitive positioning of the New England or New York transmission footprints for the next round of hyperscaler siting decisions.
The September 16 comment window is the next inflection point after August 17. Stakeholder comments in the interim shape the Commission’s read on which Section 205 filings are substantive enough to preempt Section 206 remedies and which are not. The RTOs that file thin Section 205 packages on August 17 and rely on the comment window to fill them out are running a real risk that the Commission treats those filings as inadequate and imposes a Section 206 remedy anyway.
The August 17 filing wall is not the end of the docket. It is the beginning of the redesign, and the shape of what the six RTOs put on paper that day determines the shape of the large-load interconnection rulebook for the next several years.