This report by the non-profit Small Business Majority, released June 11, found that the health care reform plans currently under debate in Congress could save small businesses $546 billion to $855 billion over ten years.  The report find that, even under a plan which requires small businesses to offer employer-sponsored care, small businesses would benefit from streamlining the purchasing process and lowering administrative costs as well as tax credits designed to defray much of the cost of the benefit.  The report found that, without reform, the cost of health care for small businesses will rise from an estimated $156 billion this year to $339 billion in 2018. 

From the report:

This study represents the first ever application of the Gruber Microsimulation model (GMSIM) to a broad range of small business success benchmarks under health reform.  The results are clear: Small businesses will be far better off under a thoughtfully reformed healthcare system based on shared responsibility among individuals, business, government and the healthcare industry - as long as such a system includes provisions that reflect the particular financial constraints faced by small businesses. Under the models considered, shared responsibility includes tax credits to enable small business owners to better afford coverage options (based on the size of the business), coupled with a payment, on a sliding scale, to be made by employers who don't offer health insurance (also based on the size of the business). 

Full report: The Economic Impact of Healthcare Reform on Small Business (PDF | 6.76 MB)  

Small Business Majority. (2009). The economic impact of healthcare reform on small business. Gruber, J. Harbage, P., Haycock, H. and the SBM Economic Advisory Council.