Let's take a family of 4 with $150K of income. Assume they contribute 6% to a 401K and pay $3k per year in pre-tax deductible health care premiums, pay a 5% state tax rate, have a $300K mortgage at 4.5% interest and a $400K property value with 1.5% real estate taxes.

Under current law their estimated taxes would be

Income...............$150,000
401K...................($9,000)
Health Ins............($3,000)
Mtg Interest........($13,500)
R/E Taxes............($6,000)
State taxable Inc..$118,500
State tax deduct...($5,950)
Exemptions..........($16,200)
Fed Taxable Inc....$96,375

They would pay 10% on the first $18,650, or $1,865, 15% on the next $57,250 (from $18,650 to $75,900) or $8,588, and 25% on the final $20,475 (from $75,900 to $96,375) or $5,119. $1,865 + $8,588 + $5,119 = $15,571.

Now let's look at their tax under the new plan. Everything is the same except they lose the state tax deduction and the $16,200 in exemptions. With the loss of the state tax deduction, the other itemized deductions only total $19,500, so they take the new higher standard deduction of $24,000. So here's what their taxes look like:

Income..................$150,000
401K......................($9,000)
Health Ins..............($3,000)
Standard deduct...($24,000)
Fed Taxable Inc....$114,000

The tax calc is simpler. They pay 12% on the first $90K of income or $10,800, and pay 25% on the next $24K of income (from $90K to $114K) or $6K. So under the new plan, their taxes would be $16,800 or $1,228 higher than under the old tax plan. The loss of the 4 exemptions is a killer.

For a family of 2 with everything else the same, the new plan saves them $800. For a family of 3, it's roughly a push. On balance, I'd bet it's a slight increase with some families saving, and some families paying more. The bigger the family and the higher the state income tax, the more likely they are to pay more under the trump plan.