The deal, stuck with the official title of "Microsoft Office Pre-launch Offer," started Oct. 19 and ends April 30, 2013. Customers who buy a retail copy of Office 2010 for Windows or one of several stand-alone applications within that period can download a free copy of the corresponding version of Office 2013, or in some cases, choose a free one-year subscription to an Office 365 plan.

Although Microsoft has announced Office 2013, provided a preview of the new suite and named prices, it has not set a launch date. Most expect Office 2013, and the Office 365 plans that rely on it, to ship in late January or early February 2013.