Top Democrats in the Oregon House and Senate say they’ve reached agreement on a corporate tax plan that would raise nearly $900 million in the next two years to patch the state’s budget hole and increase education funding, but whether it can garner business support or Republican support needed to pass a tax package remains in doubt.  The complex proposal, crafted by House Speaker Tina Kotek and Senate Revenue Chairman Mark Hass, would temporarily hike corporate income taxes and, beginning in 2019, overhaul how the state taxes businesses.  But Republican 52nd District Representative Mark Johnson says the complexity may make it difficult to garner support, and the allowance for modification of the gross receipts tax rate, once it is established, by a simple majority vote could make the business community nervous.  Johnson adds the package also lacks cost containment measures Republicans say have to be adopted to get the GOP vote in each chamber to pass a revenue measure.