i always get confused when spelling words with double letters. is there a rule to help figure out when to use double letters and when not to?

It can be pretty confusing I agree, particularly for people learning English as a foreign language. There are a few rules it's worth trying to remember. The final consonant of a word is often doubled when: Adding -ed, -ing, -er, -est in the following cases: Double up on the final "b, d, g, l, m, n, p, r and t" at the end of words, e.g. - rob - robbing - sad - sadder - big - bigger - travel - traveller - skim - skimming - win - winner - pop - popping - prefer - preferred - hit - hitting Looking at these doubled up letters, we can see that there is the following pattern "consonant - vowel - consonant" at the end of a word. For example: travel - 'vel' v - consonant - e - vowel l - consonant. Words of more than one syllable have their consonants doubled only when the final syllable is stressed. begin - beginn ing BUT open - opening defer - deferr ing BUT offer - offering When words have more than one syllable and end in 'l' always doubles the 'l', even in the case of unstressed syllables. Takes a bit of thinking about, I know. But worth the effort to learn it.

This really does help. Incoming is an odd one, I tried to use the rules but noticed that income is not where incoming is derived from. This word does not have the final syllable stressed, so it sort of fits the rules anyway. I am not learning English as a second language, however I am Australian so I guess that kind of is the case..