Garriott has headed the department since 2005 and is a holdover from former Gov. Janet Napolitano's administration. He led the tax collection agency at a time when it made hundreds of layoffs during the state's ongoing budget crisis.
Garriott is the third department director to recently submit resignations. Others are the heads of the Department of Environmental Quality and the Department of Economic Department.
The Arizona Republic reported Garriott's resignation in an blog post late Tuesday.