Martin Lewis has issued three pieces of advice for everyone on what has been dubbed "meter reading day".
Energy providers have been struggling to keep up with the volume of traffic to sites on Thursday as millions scrambled to submit meter readings ahead of the April 1 deadline.
Among the energy companies that have reported technical difficulties on the 'submit a meter reading' sections of their websites are; British Gas, EON, EDF Energy, Shell and Scottish Power - though some customers say they've been able to submit their meter readings on mobile apps instead. For the latest on the situation follow our live blog here.