GOV.UK
Working the examination: Dates for issuing notices to both claimants
If you decide to give notice to both claimants, you do not have to issue both notices at the same time, and indeed there may be good reasons for not doing so (for instance, where you requested the information informally from both at different dates). But it will normally be sensible to do so, as having a single date will make it easier for you to keep track of progress and monitor and mange future stages of the examination (such as the hearing of appeals). You should always issue a separate notice to each claimant, even if the information you require from each is the same.