Republican gubernatorial candidate Scott McInnis has refused to release his tax returns, a position that breaks from routine campaign practices in Colorado and nationally, The Denver Post reports.

GOP candidate Dan Maes also rejected The Denver Post’s request for his tax returns. Democratic candidate John Hickenlooper has pledged to release 10 years of his returns by the end of next week.

Media outlets routinely request tax returns from candidates because they reveal more than mere income: They show sources of income and potential conflicts of interest, charitable giving, the use of tax shelters, how candidates manage their own money and how their tax rates compare with the average taxpayer’s.