How Korean electricity tiers work

What progressive pricing means

Residential electricity in Korea is priced in tiers, and the price of a kilowatt hour rises as you use more. Industrial and general supply have no such tiers. Only residential supply does.

This is where the common misreading starts. Reaching the third tier does not put the whole month on the third tier rate. The slice inside the first tier is charged at the first rate, the slice inside the second at the second rate, and only the slice above the boundary carries the higher rate. Crossing a line does not multiply the whole bill.

The standing charge behaves differently. It is a single figure chosen by the tier your monthly total lands in, and it rises with the tier. So at a boundary there are two jumps at once: the rate on the next kWh, and the standing charge on the whole month.

What draws the tiers

Two things draw them: the season, and whether you are supplied at low or high voltage.

The season splits into summer and everything else. Summer runs from 1 July to 31 August, and the tiers widen for it. The first boundary moves from 200 kWh to 300 kWh and the second from 400 kWh to 450 kWh. The same 250 kWh sits in the second tier in June and in the first tier in July.

Low and high voltage is about how the electricity reaches you. Houses and most low rise flats are low voltage. Many apartment complexes take high voltage and split it between units. High voltage has a lower standing charge and lower rates. Your bill says which one you are on.

One more line sits on top. In summer and in winter, anything above 1,000 kWh in a month is charged at the super user rate. Winter here runs from 1 December to the last day of February. In spring and autumn that line does not exist.

The order this calculator works in

First the usage is split across the tiers. Each slice is multiplied by its own rate and the results are added: that is the energy charge. Then one standing charge is added, taken from the tier the monthly total lands in.

The climate and environment charge comes next. It ignores tiers and applies to every kWh at a flat rate. KEPCO's page states that the rate is the sum of the renewable portfolio standard cost, the emissions trading cost and the coal generation cutback cost.

Standing charge, energy charge and climate charge together make the electricity charge. VAT and the electricity industry fund levy sit on top of that. Article 30 of the Value Added Tax Act sets the VAT rate and Article 36 of the Enforcement Decree of the Electric Utility Act sets the levy. We read both texts on the day this was built and cite the article numbers on the rate tables page.

Each line is rounded to the won. How the bill itself rounds we could not confirm from the source, so the page says plainly that the rounding here is ours. The authority on what you owe is the bill KEPCO sends you.

What to read off the bill

Three things go in: the usage, the month, and low or high voltage.

The usage is printed in kWh on the bill and in the KEPCO app, labelled 당월 사용량. It runs from one meter reading to the next, so it is not the calendar month. With a reading on the 15th, the month runs from the 15th of last month to the 14th of this one.

For the month, pick the month the bill is for. When a reading period straddles June and July the tables are applied to each part separately, while this page treats a month as one season. A month on that boundary can therefore differ from the bill.

Low or high voltage is printed on the bill. If you cannot find it, houses and low rise flats are usually low voltage and apartment complexes are usually high voltage.

Working from appliance hours

When you do not know the usage yet, work from the appliance. Multiply the wattage by the hours a day and the number of days and divide by 1000 to get the kWh it adds in a month. 600 W for 8 hours over 30 days is 144 kWh.

The wattage is on the plate at the side or back of the unit, or in the manual. Air conditioners often print a cooling figure and a rated figure; the cooling figure is closer to what it draws while running. This calculator fills in no default wattage, because it differs by unit and we do not know yours.

What comes out is an assumption. An inverter unit drops its draw once the room reaches the set temperature, so it does not hold the plate figure all the way, and hotter weather pushes it up. The page says so where the number appears.

To see what one more appliance costs, the page calculates the bill twice and subtracts. It does not multiply by a single rate. Crossing a boundary changes the standing charge too, so multiplication gets it wrong.

Where people get stuck

Your bill and this total can differ. The fuel cost adjustment is missing here, and so are welfare discounts and large household rates. The fuel adjustment is set quarterly and we could not confirm the current figure from the source, so only the published annual cap appears on the rate tables page.

The month you pick and the period on the bill can be out of step. When a reading period spans two seasons the tables are applied to each part, while this page treats a month as one season.

If you are over 1,000 kWh and see no super user line, check the month. That line exists only in summer and winter.

If one extra kWh at a boundary seems to move the total a long way, look at the standing charge. The energy rate applies only to the slice above the line, but the standing charge is a single figure for the whole month and it changes all at once.