The energy regulator is consulting on new rules to change licence conditions so it can use enforcement action if suppliers fail to meet the three week switching requirement.
Current rules rely on consumers taking action if they are not transferred to their new supplier within three weeks of making their switch, following a 14 day cooling off period.
Ofgem is also consulting on rules to ensure cases where customers are mistakenly switched are “stamped out”.
Research by the regulator in December revealed that 1 per cent of all transfers were erroneous, while more than 20 per cent of electricity and more than 80 per cent of gas switches in the domestic sector were taking longer than three weeks.
The consultation, which opened today, closes on 12 May, and Ofgem hopes to have the new rules in force by August this year.