Basically, for income tax, a flat tax of around 25% for all with a maximum of 5% reduction for donation to charity. Adjust tax rate for all as necessary. Capital gains, inheritance, etc, are income. No earned income credit, no family credit, no marriage deduction, etc. At the end of the year, you earned x number of dollars during the year after including losses and then give the government 25% of it.(or whatever other rate meets our needs).
For Corporations, lets say around 15% for those who have 5% or less profits, 25% for those with between 5-10% profits, 35% for those earning between 10-20% profit and 75% for any corporation earning greater than 20% profit. Taxes apply for only those profits earned in the United States, it's territories or protectorates.
Tariffs are applied equal to what the other country taxes our products entering their country. If there is a relief of tariffs if the company produces in the US, it is only applied to those products produced in the US. If someone like Toyota only assembles in the US, then we tariff the parts coming in but not the finished model assembled here.
Government spending is reduced to only those items which are a benefit to all Americans, not a limited number of them. Since Social Security and Medicare are separate tax items, independent of federal income tax withholdings, then they are separated from governments direct control. Like the post office, the government sets it up, but then only chooses it's head and cannot take anything from it. If the final analysis shows that simply buying all seniors and disabled persons a private insurance policy with acceptable co-pay is more cost effective, then we do that instead of the government running the whole show and making the mess of it as they have.