During my writing adventures, I have come across words that have (to me, anyway) odd-looking spellings. I plan to post these here, in case you find yourself questioning your own spellings. Also, some spellings depend on whether you are following American English or Standard British English. Keep in mind, Microsoft Word sometimes accepts either spelling - which will confuse you. Confused yet??
Now, is it Benefitted or Benefited?
The rule we learned as kids was to double the last consonant before adding -ed or -ing. However, the actual rule is to only double when the last consonant is stressed, such as permit (permitted, permitting). The stress is on the "mit" part.
In the case of benefit, the stress is not on the last part. So we do not double the last consonant. The correct spelling is BENEFITED.