The federal government has been making several changes to the tax laws in order to stimulate investment in business. Among these changes are the availability of "bonus" depreciation and the amount of Sec 179 deductions available. Please note that as in prior years such treatments were enacted on the federal level, Pennsylvania has not acquiesced to these changes. Therefore your business taxable income may be greatly different for federal and state purposes.
There are many more changes and maybe some still to come. Last year, Congress fiddled with the tax law until December 22nd. We may be in for tax laws being enacted as late as that again this year.