In the example you give, the anniversary date would be 23.4.09.
The anniversary referred to is of the LHA date, which itself refers to the ‘relevant’ date used to determine the LHA, which includes the date of claim.
Interestingly, new regulation 8 of the D&A regs sets the effective date for the resulting superseding decision as the beginning of the benefit week in which a determination is made. If made promptly, then the new LHA value would apply from 21.4.09.
