OATT: the tariff that makes transmission service non-discriminatory
The filed tariff under which a transmission provider offers transmission and interconnection service on terms that do not favour its own generation.
An open access transmission tariff is the filed document under which a transmission provider offers service. Its purpose, established in FERC Order No. 888 and carried forward since, is to ensure that a utility owning transmission cannot use control of the network to advantage its own generation.
The tariff contains the terms of point-to-point and network transmission service, the rates and formula rates that apply, the ancillary service arrangements, and, as attachments, the interconnection procedures and pro forma agreements that govern how new generation connects.
Because the tariff is the governing legal instrument, almost every question about interconnection in a specific region resolves to a question about tariff language. Changes are made by filing at FERC under the Federal Power Act, and each filing carries a docket number under which the proposal, protests, interventions and the Commission''s order can be read.
Questions
- Where do interconnection procedures live?
- In the open access transmission tariff, usually as attachments containing the large and small generator interconnection procedures and agreements.
- How is a tariff changed?
- By a filing at FERC, which the Commission accepts, rejects or sets for hearing. The filing and its record appear in a docket.
Sources
- 01
Improvements to Generator Interconnection Procedures and Agreements, Order No. 2023
Federal Energy Regulatory Commission · RM22-14-000 · retrieved 2026-08-09
- 02
Pro forma Large Generator Interconnection Procedures and Large Generator Interconnection Agreement
Federal Energy Regulatory Commission · pro-forma-LGIP-LGIA · retrieved 2026-08-09