Households will receive clearer energy bills under new rules that come into force today.
All gas and electricity statements will include each household's current energy plan, your past year's consumption (if you've been a customer long enough) and predicted bill (if you've been a customer for at least a year).
In addition, separate annual statements will include comparisons with other deals offered by that supplier.
Crucially, these will not include comparisons with rival suppliers, which could be cheaper, though it will be made clear that you can switch provider.
Given the complicated nature of the energy market, confusion may still occur.
You usually pay more for the first set of units of energy you use in a billing period than for later units. Even then, it is not clear what a unit represents in terms of consumption, unlike a phone bill.
Consumer Focus spokesman Adam Scorer says: "We are disappointed at how some suppliers are implementing these changes and want to see clear English on bills for customers."
How to switch supplier
Households can sometimes cut their bills by hundreds of pounds a year by checking the tariffs available via a specialist comparison site and switching, if necessary (see the Compare Gas & Electricity and Get Cashback guide).
Those languishing on their supplier's standard tariff or who get bills through the post are almost certainly paying too much.
While the cheapest online deals for typical users are less than £900 a year, those on a standard tariff typically pay around £1,200.
Pre-payment meter warning
Ofgem also said today that annual premiums those with prepayment meters pay compared to those you pay by direct debit dropped by 38% (£111 to £69) following its overhaul of industry regulations.
However, Ofgem is investigating two suppliers for continuing to overcharge.
Ofgem's Sarah Harrison adds: "Unjustified premiums have fallen significantly. However, we have made it clear to the two suppliers concerned we will take action if the differentials cannot be justified."
Additional reporting by the Press Association.
Further reading/Key links
Slash energy costs: Cheap Gas & Electricity
Your rights: Fight Energy Direct Debits
Capped tariff help: Is Your Cap/Fix Ending Soon?
Boiler protection: Boiler Cover