Koch-backed seniors group low-balling election spending?

www.publicintegrity.org/2014/07/30/15163/koch-backed-seniors-group-low-balling-election-spending
"The 60 Plus Association — a nonprofit senior citizen advocacy group funded largely by billionaire businessmen Charles and David Koch’s conservative political network — appears to have vastly understated its level of election spending on federal tax filings, a Center for Public Integrity review of documents indicates."