Link Drop Down List & Lookup Corresponding Information

I'm trying to categorise a load of expenses against their appropriate budget and sub-budgets. I've got all the budget subcategories in separate dynamic named lists each headed by the main budget name. I want to be able to select the main budget name e.g. marketing or sales etc and then see, in the next column over, only the appropriate subcategories to select from e.g pick the appropriate dynamic list (I've used dynamic lists so I have some flexibility to add new categories at a leter date).