Tax authorities say a man in Hokkaido failed to declare more than roughly ¥400 million in income from horse race betting over six years, determining that the money spent on losing tickets does not count as expenses, sources said Monday.

The man, a 41-year-old civil servant, is believed to have been asked to pay more in back taxes, including an additional tax, than the about ¥570 million he had actually earned from horse race betting.

The man profited every year between 2005 and 2010 from betting on Japan Racing Association horse racing every week but failed to declare his income from the activities, the sources said. He was investigated by the Sapporo Regional Taxation Bureau as a result.

The man subsequently declared about ¥570 million as miscellaneous income after adding the cost of buying tickets that turned out to be losers to his expenses.

The amount he declared was the difference between the money he had spent on betting and the money he had collected with winning tickets.

But the tax bureau determined the money from winning tickets to be occasional income in accordance with a notice from the National Tax Agency.