How to increase tax file

My Child will just be 18 and I want to plan my fixed income from my child accounts so that I can get atleast 2.5 lakh income tax free. How should I do that ? Need tax planning suggestions to increase file each year for my child showing income and deploy that under fixed income. What income should I show which could be less than 2.5 for my child. I suppose this is tax planning and not tax evasion.