The Applicable Fallback Effective Date, as defined in the 2021 ISDA Interest Rate Derivatives Definitions, Section 8.5.4. The date upon which the fallback rate becomes effective. This means that any rate observation for that date or for any subsequent date would use the fallback rate rather than the originally defined rate. This date will typically immediately follow the cessation of publication of the original term rate but could occur before that (e.g. if the original rate is deemed non-representative prior to cessation of publication). If the effective date occurs within a calculation period with multiple rate observations (because of averaging), observations prior to the effective date will use the original floating rate index, and observations on or after the effective date will use the fallback rate.