Person referred to in sec 160(1)(3) &(4)

Itr 5 is applicable for aop, boi, business trust etc.
when the members have income other than income of aop then if such Income exceeds basic exemption limit then maximum marginal rate is applicable @ 30% plus surcharge @ 25% or 37% on certain conditions plus cess @ 4%. When such maximum marginal rate is applicable then such income is exempt under aop.

But if such Income doesn't exceeds basic exemption limit then normal tax rate is applicable and it is taxable in aop and rebate u/s 86 will be applicable on the basis of average tax rate