I am unable to provide a calculator suitable to your model. However, I hope, the attached spread sheet will be handy to work out taxable income and IT applicable under extant Indian IT act, a ready made solution for the Fin.Year 2018-19. You may fill up the cells with appropriate figs. & details and there you'll get the ultimate solution. You also can browse the net and locate any other computation models for your requirement. But I doubt any available on the lines of your xl sheet. If you'll have any other specific queries, pl.raise here.
5th November 2018 From India, Bangalore