I am taking over another firm which already has an ISBN allocation. All future books will be published under my publisher name. Can I renumber all the other firm’s titles? 

Not until they are reprinted under your own publisher name or imprint and carry your publisher name – at this point you may assign ISBNs from your own allocation to the books. Before then the books should continue to use the existing ISBNs of the original publisher

What happens if I have used all the numbers under my identifier prefix? 

An additional identifier prefix can be assigned – allowing for a larger output if necessary. This is an additional identifier prefix and not a replacement.

We have changed our publishing name and will no longer use our former publishing name in the future. What happens to our ISBNs? 

You should notify your national ISBN Agency that you have changed your publishing name so that they can record this new name against your existing ISBN allocation. You should continue assigning any remaining unused ISBNs to books that you publish under your new name. If you reprint (or bring out a new edition or new format of) a book that you previously published under your former name, then you must assign a separate ISBN from your allocation to this version. You should also state your new publisher name on the title page, title verso (copyright page), cover, spine and anywhere else that the publisher name is given.