Melissa was sent a £4,500 bill for energy used two years ago

Imagine moving out of your home, only to get hit with a £4,500 energy bill two years later – that’s exactly what happened to Melissa Penn.

She told BBC’s Money Box she was stunned when a bill arrived for energy used at her old address.

Melissa’s story

Melissa doesn’t believe the bill is accurate.

Even if it is, the rules on ‘back-billing’ mean she doesn’t have to pay. Under these rules, companies can’t demand payment for energy used more than 12 months ago.

But that didn’t stop the letters from arriving, each for varying amounts.

Melissa’s bill was cancelled after four months.

She said: “The whole process was extremely long and extremely stressful.”

What is back-billing?

Back-billing is essentially a ‘catch-up’ bill, sent when energy companies charge you for energy you’ve used in the past.

Ofgem rules say you can only be back-billed for gas and electricity used in the last 12 months.

So if you’ve been undercharged, your provider only has a year to send you the correct bill.

The reality of back-billing

More than 3,300 cases of back-billing were reported to the energy ombudsman in the 12 months to September 2024.

Energy UK, which speaks for suppliers, says this makes up a small number of complaints.

Ofgem says the rules are clear and energy companies can’t ask people for money for energy used over a year ago.

Top tips to avoid and sort out issues

Energy UK advises getting a smart meter or submitting regular meter readings to help make sure bills are accurate and any issues are spotted early.

If you find yourself in a similar situation to Melissa:

• You don’t have to pay bills for energy used over 12 months ago.
• Contact your supplier – if they don’t sort it out, you can get in touch with the energy ombudsman after eight weeks.