The most sweeping tax overhaul in three decades brings lots of good cheer for businesses, ranging from a lower corporate tax rate to big tax savings for asset purchases. But there are also some deductions that disappear and other breaks that are pared back to offset part of the massive cost of the tax cuts. Here's a look at some of the key provisions in the new tax law that affect small businesses. Unless otherwise stated, most of these apply beginning in tax year 2018.

Corporate Tax Rate Slashed

Getty Images

The new law reduces the income tax rate on regular corporations (sometimes referred to as C corporations) from a top rate of 35% to a flat 21%. Personal service corporations also get the 21% rate. Although this low rate is a boon for most companies, some small C corporations could actually end up paying a bit more. That's because the law didn't keep the 15% corporate rate on the first $50,000 of taxable income. For example, a C corporation with $30,000 of taxable income will pay $6,300 of tax when it files its 2018 federal return