I have client capable of prepaying monthly medical insurance premiums for year, before year 2018 ends.  I seem to remember medical insurance premiums paid in current year for up to one year in advance are deductible for cash basis taxpayers.  However, I am not sure if that is true only for deducting as itemized deduction, or if prepaid medical insurance for up to one year is also deductible as adjustment to income, assuming taxpayer is self employed and has net schedule c in excess of total medical insurance premiums paid.