When someone says "is off with you", it may sound a bit confusing in terms of spelling. However, by using the International Phonetic Alphabet (IPA), we can better understand how to spell this phrase phonetically. The /ɪz/ in "is" is pronounced as the short 'i' sound while the /ɒf/ in "off" is pronounced as a short 'o' sound. The /wɪð/ in "with" is pronounced with a glottal stop and a voiced 'th' sound. Ultimately, the proper spelling for this phrase is "is off with you."