The Overseas Press Club (OPC) of America honoured the Financial Times and ProPublica’s Tax Wars series with the 2011 ‘best online investigation’ prize in its annual awards ceremony in New York last night.

OPC award judges “were impressed by this illuminating account of how banks took advantage of gaps in two countries’ tax laws and how the US government lost billions in the process. The four part series also delved into how a simple rule change, meant by the US treasury to cut paperwork, turned into one of the biggest international tax breaks around. Interactive graphics and charts made this four-part series even more compelling.”

Lionel Barber, editor-in-chief of the FT, commented: “The ‘Tax Wars’ series, one facet of a broader political debate in the US and UK over corporate profits, tax fairness and global competition, illustrates how the FT uses cross-platform reporting to illustrate an opaque yet vital news topic to its global audience. We are honoured to receive this recognition from the OPC.”

Contributors to the series included the FT’s Vanessa Houlder, Megan Murphy, Benjamin Freese, Johanna Kassel and Christine Spolar, and ProPublica’s Jeff Gerth and Tom Detzel.

Previously, “Tax Wars” won two Society of American Business Editor and Writers (SABEW) Best in Business Awards in the “investigative” and “creative use across multiple platforms” categories.