It rather depends on the approach you choose to take. Ultimately you can trace the origin of your words back to the Latin words finalis/finis and annualis/annalis/annus. However, in English itself, there are no independent words fin (in this meaning) or ann/enn. Actually, I don't see final as a problem, because the -al is part of the original stem.
I suppose that one way would be to propose a class of 'theoretical anglicised Latin stems', which would include such stems as ann/enn, circum, phon, etc.