What is an ICAP tag

How the hour is chosen

Through the summer, New York's statewide load peaks somewhere between 4 and 6 PM on the hottest afternoons. The single highest hour of the season is the coincident peak, and in the four settled summers from 2022 through 2025 it landed in June once, July twice, and September once — always on a business day, always between 4 and 7 PM Eastern. Nothing is final until the season ends: any hotter afternoon takes the crown.

Your meter's demand during that one hour becomes your ICAP tag. A facility drawing 5 MW during the peak hour carries a 5 MW tag all the following year, no matter how efficiently it runs the rest of the summer.

Why the hour is worth so much

Suppliers buy capacity for every megawatt of tag their customers carry, at prices set in NYISO's capacity auctions. Those prices differ sharply by locality — New York City clears far above the rest of the state — and they roll into your bill for twelve months. A megawatt of tag avoided during the one hour that counted keeps that money, every month, all year.

Spot auction results are published monthly by locality on NYISO's ICAP market pages. The calculator takes your rate; your bill or your supplier has the number.

The catch

You only learn which hour counted after the season closes, months after it happened. Curtailing every hot afternoon costs production; curtailing none wears the full tag. And unlike the five-peak programs, there is no partial credit here — the season is one hour, hit or miss.

That is what the live NYISO dashboard answers each business morning by 10 AM ET, and the track record shows how those calls have graded: three of the four season peaks across 2022–2025, flagging about five to six days a summer for a one-hour target.

ICAP is capacity. Delivery rides other peaks.

Your utility's delivery charges may key off different peaks — some bill on your own non-coincident maximum, some on the utility system peak. Those usually land on or near the statewide peak day, so curtailing the right afternoons often trims more than one line of the bill at once.