Here’s when it will affect you

The business world will see the corporate tax rate drop permanently to 21 percent, from 35 percent, beginning Monday.

Additionally, starting in 2018 interest deductions will be limited to 30 percent of earnings before interest, taxes, depreciation and amortization. And starting in 2022, the 30 percent in interest deductions will no longer include depreciation or amortization expenses. Under the current rules, companies can deduct 100 percent of interest payments from taxable earnings.

Retroactive from Sept. 27 and extending to the end of 2022 is a period of full and immediate expensing — an allowance for businesses to deduct the cost from assets acquired instantly. That will be phased out, at a 20 percent reduction per year, until it ends in 2026.

Lastly, research and development investments may be written off for five years, effective beginning in 2022, and a tax credit will be available from 2018 to the end of 2019 for businesses providing paid family and medical leave.