At Ontario Electricity Rates, Here's When ULO Beats TOU

Ontario electricity rates are fixed until October 31, 2026. On those prices, the ultra-low overnight plan (ULO) beats time-of-use (TOU) once 46.1% of your power is used between 11 p.m. and 7 a.m. That assumes even use through the rest of the day. In a month under the tier threshold (the amount tiered bills at its lower price), tiered beats both clock-based plans until 47.2% of your use is overnight. Keep weekday 4 to 9 p.m. use at half your usual rate and ULO's bar against time-of-use drops to about 30% to 31%. At twice your usual rate, it climbs to about 59%. In the regulator's own bill calculator, ULO wins only for a heavy electric-car driver who charges at night.

Ontario electricity rates until October 31, 2026

The Ontario Energy Board (OEB) sets one set of prices for the province under the Regulated Price Plan. These are the prices households pay when they buy power from their local utility. They cover the Electricity line of your bill only. You pay by the kilowatt-hour (kWh), the unit your meter counts.

You can pick one of three plans:

• Time-of-use is the default. It charges 9.8 cents a kWh off-peak, 15.7 cents mid-peak and 20.3 cents on-peak.
• Tiered ignores the clock. It charges 12.0 cents for your first 600 kWh a month from May 1 to October 31, or your first 1,000 kWh from November 1 to April 30. Everything above that costs 14.2 cents.
• Ultra-low overnight charges 3.9 cents every night from 11 p.m. to 7 a.m., but 39.1 cents on weekdays from 4 p.m. to 9 p.m.

The OEB's price report says it sets all three so each plan's typical customer pays the same average, 12.8 cents a kWh.

Two rows decide most of it. Every kWh you use overnight saves 5.9 cents on ULO. Every kWh you use on a weekday from 7 p.m. to 9 p.m. costs 29.3 cents more. So one kWh in that evening slot cancels the overnight saving on about five kWh (29.3 divided by 5.9 is 4.97).

How much overnight use ULO needs

We priced a month of use hour by hour. You pick a share of your power for the 11 p.m. to 7 a.m. window. The rest is spread evenly over every hour from 7 a.m. to 11 p.m., weekdays and weekends alike. Holidays are left out.

That simple shape tracks the OEB's own numbers. With even use around the clock, it splits 64% off-peak, 18% mid-peak and 18% on-peak on a time-of-use bill. That's the split the OEB assumes for its typical customer. At 40% overnight it comes close to the OEB's typical ULO customer too.

The result is a break-even, the point where two plans cost the same. On even daytime use, ULO beats time-of-use once 46.1% of your use falls between 11 p.m. and 7 a.m. That holds at 400, 700 or 1,000 kWh a month, because both plans charge by the kWh. It also holds in summer and winter, since a time-of-use weekday has six mid-peak and six on-peak hours in both seasons.

Tiered depends on your total use. Under the threshold, it costs a flat 12.0 cents a kWh. On even daytime use, time-of-use can't beat that until 49.9% of your use is overnight, and ULO gets there first, at 47.2%. Above the threshold, time-of-use gets a narrow window.

Your time-of-use bill can test tiered for you, because it lists your kWh in each period. If mid-peak and on-peak are about equal, tiered beats time-of-use in a month under the threshold unless off-peak is at least 73.2%. At 700 kWh in summer that bar is 69.3%, and at 1,000 kWh it's 62.4%. The OEB's typical customer sits at 64%.

That same bill can't show your overnight share, because off-peak lumps 11 p.m. to 7 a.m. in with evenings and weekends. The hourly data in your utility's online account can. Hydro One's my Account will estimate a switch from your past 12 months, once you have at least 90 days of billing history.

Your weekday evenings move the line

Even daytime use is a model, and your weekday 4 to 9 p.m. hours matter most. We reran the break-even with those five hours used at a different rate from the rest of your day.

Light evenings can make ULO pay without a car. Heavy ones push the bar past half.

One household, worked through

Take a home that uses 840 kWh a month, spread evenly around the clock. That's 280 kWh overnight and 560 kWh from 7 a.m. to 11 p.m. A week has 112 of those daytime hours. On time-of-use, 30 are mid-peak, 30 on-peak and 52 off-peak, so 560 x 30/112 = 150 kWh mid-peak. On ULO, 55 are mid-peak, 25 on-peak and 32 weekend daytime.

Add an electric car that takes 400 kWh a month, all charged after 11 p.m. That matches the OEB calculator's "heavy usage" driver, at 24,000 km a year. The home now uses 1,240 kWh, and 680 kWh of it, or 54.8%, is overnight.

Time-of-use. Off-peak is 940 kWh: 280 overnight, 400 for the car, and 260 on weekday evenings and weekends. That's 940 x 9.8 cents = $92.12. Mid-peak is 150 x 15.7 cents = $23.55, and on-peak is 150 x 20.3 cents = $30.45. The Electricity line is $146.12.

Ultra-low overnight. The 680 overnight kWh cost 680 x 3.9 cents = $26.52. Weekend daytime is 160 x 9.8 cents = $15.68. Weekday mid-peak is 275 x 15.7 cents = $43.18, and 4 to 9 p.m. is 125 x 39.1 cents = $48.88. Each line is rounded to the cent, as a bill does. The total is 26.52 + 15.68 + 43.18 + 48.88 = $134.26.

ULO saves 146.12 minus 134.26, or $11.86 a month. Tiered costs the most: 600 x 12.0 cents plus 640 x 14.2 cents, or 72.00 + 90.88 = $162.88 in summer. In winter, on current prices, it's 120.00 + 240 x 14.2 cents (34.08) = $154.08.

Now take the car away. On time-of-use the home pays 540 x 9.8 cents ($52.92) plus the same $23.55 and $30.45, so $106.92. On ULO it pays 280 x 3.9 cents ($10.92) plus the same three daytime lines, so $118.66. Tiered wins: 72.00 + 240 x 14.2 cents = $106.08 in summer, and 840 x 12.0 cents = $100.80 in winter.

With a 200 kWh car instead, the calculator's "medium" driver, the home sits at 46.15% overnight. ULO and time-of-use then land 6 cents apart: 18.72 + 107.74 = $126.46 on ULO, against 72.52 + 54.00 = $126.52 on time-of-use. In winter, tiered beats both, at 120.00 + 40 x 14.2 cents = $125.68.

What the regulator's own calculator shows

The OEB bill calculator has seven built-in households: a typical home at 700 kWh, and six car owners. The cars take 100, 200 or 400 kWh a month, charged either "any time" or "mostly overnight". We ran all seven through the calculator.

ULO came first for one of the seven: the heavy driver who charges mostly overnight, at 51.2% overnight. On ULO that household pays 49.03 on-peak + 37.82 mid-peak + 16.71 weekend + 21.96 overnight = $125.52. On time-of-use it pays 27.02 on-peak + 20.38 mid-peak + 82.04 off-peak = $129.44. The other six are all under 46.1% overnight, and all six pay more on ULO. On the winter figures, tiered is cheapest for six of the seven.

Alectra Utilities tells customers the difference "is not likely to be more than a few dollars per month." That's true of the typical home, where the three plans sit within 89.89 minus 84.00, or $5.89, of each other in winter. It isn't true of the driver who charges any time: ULO would cost 182.92 minus 138.73, or $44.19 a month more than time-of-use.

November 1 resets the numbers

The OEB is required by law to set these prices every year, taking effect November 1. It announced the last three resets on October 19, 2023, October 18, 2024 and October 17, 2025. As of September 28, 2026, the OEB's newsroom shows no price announcement for November 1, 2026. On that pattern, expect the new prices in the third week of October, about two weeks before they apply.

Two seasonal changes land that day as well. Time-of-use moves to winter hours, with on-peak on weekdays from 7 to 11 a.m. and 5 to 7 p.m. The residential tier threshold rises from 600 kWh to 1,000 kWh. ULO's hours stay the same all year.

New prices move the break-even. On the prices in force from November 1, 2024, ULO overtook time-of-use at 42.0% overnight on even daytime use. The November 2025 prices pushed that to 46.1%. So check your plan again once the new prices are out.

What a plan saving is worth on your bill

The Ontario Electricity Rebate is 23.5% of your bill before tax, under Ontario Regulation 363/16. It rose from 13.1% on November 1, 2025. The OEB puts it at about $36 a month for a typical 700 kWh home. It's applied for you, and the OEB says switching plans doesn't change whether you get it.

The rebate is a share of a total that includes the Electricity line. So when a plan cuts that line, the rebate shrinks a little too. HST of 13% is charged on the same pre-rebate total. The OEB calculator shows both on a Toronto Hydro bill: a $164.79 total gets $21.42 of HST and a $38.73 rebate. It's the same 700 kWh, but the rebate is above $36 because Toronto Hydro's delivery charge makes this bill bigger than the OEB's typical one. So a dollar saved on the Electricity line is worth 1 minus 0.235 plus 0.13, or about 89.5 cents, on your final bill. The worked household's saving becomes 11.86 x 0.895 = $10.61.

Switching also moves the Delivery line slightly, because power lost in the wires is priced at your plan's rates. In the calculator's summer run, the Delivery line is $71.46 on time-of-use, $71.48 on ULO and $71.76 on tiered. The rest of your delivery charge is set for your local utility, and it doesn't change with your plan.

How to switch at 10 GTA utilities

Your local utility makes the switch, not the OEB. The rules come from the OEB's Standard Supply Service Code. Your utility must post an election form (the switch request) and accept it by email or mail. It must reply within 10 business days. A form that arrives at least 10 business days before your next billing period starts must take effect then. Otherwise it can wait one more period. Section 3.5.10 lets you switch again at any time.

We read the price-plan pages of 10 GTA utilities. Your bill names yours. Alectra's service list includes Mississauga, Brampton, Vaughan, Markham, Richmond Hill and Aurora, and Elexicon lists a contact line for Ajax, Pickering and Whitby. All 10 say you can switch again or switch back. One sets a limit: Alectra processes one rate option selection per monthly billing cycle.

Some homes can't switch. That includes a condo unit billed by a sub-metering company, a home on an energy retailer's contract, and a meter that can only bill tiered prices. When you leave a retailer, Toronto Hydro and Oshawa Power put your first bill on time-of-use, whatever plan you pick.