an IOU

この人の釈明を聞くにつれて元東京知事だった人のことを思い出すのは私だけでしょうか。

Your Party leader allegedly borrowed 800 mil. yen without reporting

The huge amount borrowed and the alleged failure to report it were first revealed by DHC's Yoshida in the Weekly Shincho magazine that went on sale Wednesday.
Yoshida told Kyodo that he wired to Watanabe's personal bank account 300 million yen in 2010 and 500 million yen in 2012 following requests from Watanabe's side for election campaign funds.

While Yoshida has an IOU from Watanabe for the 300 million yen, he has not received one for the 500 million yen, Yoshida said, adding that although some of the money has been paid back, around 550 million yen has yet to be repaid.

In contrast, Watanabe's May 2013 assets report showed that he had borrowed 250 million yen as of December 2012, far less than the amount Yoshida says the lawmaker owed him.
None of the reports filed between 2009 and 2012 by Watanabe's three political organizations, his party and the party's Tochigi Prefecture chapter lists any donation or borrowed amounts equal to the 800 million yen provided by Yoshida.

Of the failure to list the borrowed money, Yoshida said, "I didn't think that has not been listed."

http://mainichi.jp/english/english/newsselect/news/20140327p2g00m0dm034000c.html

基本的なフレーズですが、IOUを取り上げます。これはI owe you.の頭文字をとった略号で「借用書」を意味します。そこからさらに会話では「つけ」という意味でも用いられます。（GP）