Why is the word permitting spelled with two t's?

Answer 1

When suffixes such as -ed and -ing are added to words with the accent on the final syllable, they may double a single consonant at the end (this rule has several exceptions). In some cases, it avoids confusion with another word that drops a final E (hopping/hoping).

T words that do this include

admitting

permitting

quitting

remitting

submitting

Answer 2

The word "permitting" is spelled with two t's because it follows the rule of doubling the final consonant when adding a suffix that begins with a vowel (in this case, -ing). This helps to preserve the short vowel sound in the preceding syllable.