Only if it meets the conditions within the Debt Category Specific Provisions at section 13 of the Specification, specifically 13.2(a), which states:

(Separate Matter Starts will generally be justified where:) More than one debt is disputed on separate, substantive grounds

Which means that you would have to be challenging liability in respect of (at least) two debts within the client's case to be able to separate them out into separate matters. If it were just a bundle of debts with only one liability challenge then it's only one matter

This, I believe, is the accurate interpretation of the relevant section. I have heard, however, of one private practice contractor managing to convince the LSC (as part of the recent multiple matters investigation) that providing it met 5.8 then it was fine to separate them. From what I heard, the auditor/account manager didn't argue with this despite what it says in the Category Specific rules and the fact that the Specification clearly states that the Cat Specific rules (in this case, 13.2) over-ride the General Provisions (such as 5.8) where any conflict exists. This is only anecdotal of course