I believe the tax code should be simple and straightforward. There is no need for a system where the more you make the more they take. It punishes those who are successful.
I propose a simple % flat tax on all earned income that excludes tips and social security that President Trump has already announced he plans to cut. I would also structure the simple flat tax that would go with good family value incentives. If you file single flat tax would be 15%. Married couple would be 10%. Child tax credits would not be available until you have more kids than the national average and it would only be per kid over the average.
Currently the national average is 1.94 kids per family so having two kids would grant you the tax credit. The second the average gets to 2.01 the credit would go away until you have another child to put you over the average. I would let those smarter than me figure out what the tax credit would be but $2000 per child over the average would be a good start.
Now with this being a much simpler system there would be no need for such a large government agency such as the IRS. I would get rid of them or drastically reduce the size to a fifth of what it is. I would let those more well versed in this than me figure out the rest.