The Job Creation and Worker Assistance Act of 2002 (JCWA) provided an additional depreciation deduction in the placed-in-service year that is equal to 30% of the adjusted basis of the qualified property placed in service after 9/10/01. This law is reflected (for the most part) in IRS Code section 168(k).
The Jobs and Growth Tax Relief Reconciliation Act of 2003 (JGTRRA) amended the bonus depreciation provisions of the Job Creation and Worker Assistance Act of 2002. For qualified property placed in service between 5/6/03 and 12/31/04, the bonus depreciation increased from 30% to 50%.
The Economic Stimulus Act of 2008 allows 50% bonus depreciation for qualified property placed in service between 1/1/08 and 12/31/08.
The American Recovery and Reinvestment Act of 2009 allows 50% bonus depreciation for qualified property placed in service between 1/1/09 and 12/31/09.
The Small Business Jobs Act of 2010 allows 50% bonus depreciation for qualified property placed in service between 1/1/10 and 12/31/10.
The Tax Relief Act of 2010 allows 100% bonus depreciation for qualified property placed in service between 9/9/10 and 12/31/11 and 50% bonus depreciation for qualified property placed in service between 1/1/12 and 12/31/12.