"The Children’s Health Insurance Program Reauthorization Act of 2009 (“Act,” Public Law 111-3), was signed into law on February 4, 2009.  The Act increases the Federal excise tax on all tobacco products and cigarette papers and cigarette tubes, effective April 1, 2009.  In addition, the Act imposes a floor stocks tax on all tobacco products (except large cigars), cigarette papers and cigarette tubes held for sale on April 1, 2009." For more information visit the Alcohol and Tobacco Tax and Trade Bureau (TTB) at ttb.gov.

Here is the Floor Stocks Tax Return Form and Floor Stocks Tax Return Instructions.

UPDATE:  The Alcohol and Tobacco Tax and Trade Bureau (TTB) has recently posted a list of Floor Stocks Tax Frequently Asked Questions here.