For our final example, we’ll assume the W-2 wages were $350,000, qualifying dividends and capital gains1 were $15,000, and other income was $10,000.
Itemized deductions in 2017 were $32,000 in SALT, $20,000 in deductible mortgage interest on the principal residence, and $20,000 in charity for a total of $72,000. Personal exemptions were $4,050 per person in 2017. However, the old tax law limited itemized deductions and personal exemptions for higher-income taxpayers. Those limitations are reflected in the comparison below.
| Description | Total | 2017 | 2018 |
| Taxes | 32,000 | 32,000 | 10,000 |
| Charity | 20,000 | 20,000 | 20,000 |
| Mort. Interest | 20,000 | 20,000 | 20,000 |
| 2017 reduction | -3,045 | ||
| Allowed | 72,000 | 68,595 | 50,000 |
Using this data, here is the comparison in old and new tax law:
| Description | 2017 | 2018 | Change |
| AGI | 375,000 | 375,000 | |
| Pers. Exempt. | 324 | 0 | -324 |
| Itemized/Std. | 68,595 | 50,000 | -18,595 |
| Taxable | 306,081 | 325,000 | 18,919 |
| Income tax | 81,706 | 86,440 | 4,734 |
| AMT | 6,185 | 0 | -6,185 |
| M/C surtax2 | 1,350 | 1,350 | |
| NIT3 | 890 | 890 | |
| Total tax | 90,131 | 88,680 | -1,451 |
The new tax law limits the state and local tax (SALT) deduction to $10,000 for all but Married Filing Separately filers (so the ‘marriage penalty’ lives on in this rule), but total itemized deductions are no longer reduced for high income taxpayers. These changes increase taxable income by 6.18% in this case. The taxpayer previously owed Alternative Minimum Tax (AMT), in this example due solely to his itemized deduction of SALT. With the elimination of AMT, the total tax bill actually fell by 1.61%. The average tax rate as a percentage of AGI fell from 24.04% to 23.65%.
1Qualifying dividends and capital gains are taxed at a lower rate for almost all taxpayers. In these examples, federal taxes were reduced by $1,950 in 2017 and $3,000 in 2018 due to this tax preference. 2Additional Medicare Tax is a 0.9% surtax on W-2 wages above $200,000 for single filers. 3Net investment tax, levied on high-income taxpayers.