The bill arrived and the amount on it startled you, even though you have not changed your consumption habits in any significant way. That leaves you unsure, especially when you do not know whether the bill is in order and you should just pay, or whether a mistake crept in on the supplier’s side. Here is what to check on the bill, how to file a complaint and what to do if the supplier does not respond or rejects it.
What to check on the bill first
Before you write a complaint, do your own check. You will catch most billing errors by comparing a few specific figures.
Consumption according to the electricity meter or gas meter. Write down the current meter reading, or photograph it, and compare it with the figure on the bill. If there was no physical reading, for example because you were not at home, consumption is calculated using a substitute value. The distributor sets it under the metering rules, in plain terms by estimate. It is the least accurate method, and this is where discrepancies most often arise.
Unit price (rate). Check that the supplier is charging the rate under your current contract, not under an older or different product. A price change during the contract must be properly notified. A unilateral increase without notice is not in order. Under Section 11a(4) of the Energy Act, the supplier must notify you of a price change no later than the thirtieth day before the day it takes effect, and not only in the case of a price increase.
Amount of advance payments. Advance payments should match your reasonably expected consumption, typically the consumption for the previous period multiplied by the current price. If you reduced consumption in the meantime and the supplier did not take that into account, it is usually just a matter of reporting the current reading.
Length of the billing period. The statutory cap is 14 consecutive calendar months. A longer billing period is not allowed. A shorter, twelve-month period applies where the offtake point is equipped with continuous metering. If the supplier sends bills at irregular or unusually long intervals, it is worth asking about it.
Personal and contract details. A wrong address, bank account or offtake point number can mean the supplier does not even return an overpayment. The payment simply does not get where it should.
When and how to file a billing complaint
If after the check you find that something does not add up, you have the right to complain about the bill. The complaint is filed in writing directly with the supplier, not with the distributor or with the Energy Regulatory Office (Energetický regulační úřad, ERÚ), which does not decide the complaint itself. The wording of the complaint matters a lot. The same rules apply as for any other complaint.
Include in the complaint:
- your identification details and the contract number or customer number,
- the number and address of the offtake point,
- a clearly stated reason and subject of the complaint,
- if you are complaining about the amount of consumption, also the electricity or gas meter reading, ideally supported by a photograph.
The law does not set a deadline by which the consumer must file the complaint. ERÚ points this out as well. It follows only from your supplier’s terms and conditions, where it is typically 30 days from delivery of the bill. Look them up and follow them. After the contractual deadline passes, a complaint is much harder to pursue. Your right does not lapse because of that. You have a general three-year limitation period for the return of an overpayment. The terms and conditions must not shorten your consumer rights.
A complaint has no suspensive effect. Even if you disagree with the bill, you must pay any outstanding balance by the set deadline. If the complaint later proves justified, the supplier will return the overpaid amount.
How long the supplier has to handle it and what to do if it does not respond
The supplier has 15 days from delivery of the complaint to handle it. If the resolution depends on another licence holder handling its own complaint first, typically the distribution system operator for meter verification, that time is not counted toward the deadline. The deadline therefore does not keep running. Nor does it automatically extend by some fixed number of days. Under the ERÚ quality standards, the supplier must then financially settle an accepted complaint within 30 days of its delivery.
If the supplier misses this deadline, you are entitled to financial compensation for failure to meet the quality standard. For electricity, under ERÚ Decree No. 540/2005 Coll., it is CZK 600 for each day of delay, up to CZK 24,000. For gas, under Decree No. 545/2006 Coll., it is CZK 750 per day, for households up to CZK 7,500. The compensation does not arrive on its own. You must request it from the supplier in writing, within 60 calendar days of the day the deadline was breached.
As of 1 August 2025, an amendment to the Energy Act added another tool. If the supplier does not handle the complaint within the 15-day deadline, or does not send you the bill itself on time, you are entitled to a penalty of CZK 50 for each day of delay, up to CZK 5,000. It is counted only from the thirty-first day of delay. You therefore get nothing for the first month of delay. It does not arise if, for the same breach, you are entitled under the contract to a contractual penalty of the same or a higher amount. The penalty does not arrive on its own. You must call on the supplier for it. Alongside it you can also claim damages that the delay caused you.
If the supplier rejects the complaint or does not respond at all, you have two main options:
- Contact the Energy Regulatory Office. This is a stronger tool than people usually expect. On your application, ERÚ will decide the billing dispute. It will assess whether the supplier billed you correctly and can order the supplier to return the overpayment. Its decision is binding.
- Consider a formal demand or going to court. If a higher amount is at stake and the supplier has not been communicating for a long time, it makes sense to send a written demand for payment with a clear deadline. Before a possible lawsuit then comes a pre-action letter, which you draft and send yourself.
The approach is very similar for telecommunications, only with different deadlines and a different authority. If you are dealing with a phone bill, go through the article on what to do when the operator charges you for a service you did not order.
Practical step-by-step procedure
- Write down or photograph the current electricity or gas meter reading and compare it with the bill.
- Check the rate, the amount of advance payments and the personal details on the invoice.
- If something does not add up, write a written complaint with identification details, the contract number and a clear description of the error.
- Send the complaint to the supplier as soon as possible and in line with the deadline in the terms and conditions (typically within 30 days of delivery of the bill); pay any outstanding balance in the meantime.
- Watch the 15-day deadline for handling the complaint and the following 30-day deadline for financial settlement if the complaint is accepted.
- If the supplier breaches the deadline, file a written request for financial compensation for failure to meet the quality standard within 60 calendar days.
- If the supplier rejects the complaint or does not respond, contact ERÚ or consider a formal demand.
What to do next
Getting every required element of the complaint right and citing the correct deadlines is tedious, especially when you are dealing with a bill for the first time. A pre-action letter, if it comes to that, you draft yourself.
Legamik is not a law firm and does not provide legal advice. In complex disputes we recommend consulting an attorney.