A taxpayer subject to the tax imposed by sections 422.33 and 422.60 shall make payments of estimated tax for the taxable year if the amount of tax payable, less credits, can reasonably be expected to be more than one thousand dollars for the taxable year. For purposes of this subchapter, “estimated tax” means the amount which the taxpayer estimates to be the tax due and payable under subchapter III or V of this chapter for the taxable year.