let say the montly IO payment is 1000, one year is 12000
the tax deductible is 12000
let say the tax rate is 25 %
then you save 3000 tax deduction
for a loan of 200k with 5 years loan and 5.5 interest rate.
the tax deduction for IO is 13250
however the interest incured in IO is higher than P&I with amount 25786
even in a short term as 5 years, IO costs more than P&I loan