I received this offer via email around 3 months ago a couple of days after requesting a quote from EDF. This offer still appears to be live and the offer code was applied to a quote when I have tested it (see screenshot below). Please note that this may not be guaranteed due to the current energy situation.
Start a new quote on EDF and then apply the code in the offer code box.
£100 credit – this offer is available until 31 December 2021. Customers who choose to sign up to a new fixed tariff via one of the links in this email will be awarded a £100 credit (plus 5% VAT). Please allow up to 60 days for the credit to be applied to your energy account (46 days, in addition to the 14-day cooling off period). GoElectric is excluded from this offer. This offer can be withdrawn at any time. Full T&Cs apply and can be found on the offer landing page.