Senate Democratic Leader Ed Murray has proposed a new capital gains tax.

Murray is proposing a 5 percent tax on capital gains to start in 2015, which he said would raise between roughly $600 and $700 million per year to help fund basic education and higher education.

He proposed something similar last year.

Under Murray’s referendum proposal, a half-cent sales tax increase would take effect on July 1, bringing in nearly $500 million to help the current budget. In 2014, the sales tax would decrease to three-tenths of one cent. In 2015, it would decrease again to two-tenths of one cent, and in 2016, it would go away completely. The capital gains tax would be permanent, and dedicated to paying for basic education in the state.

This time around, rather than the stepped-up, stepped-down sales tax changes, Murray proposes extending the temporary beer and business axes scheduled to sunset this year.

The News Tribune says the idea is a likely non-starter. As we’ve written before, the capital gains tax is a bad idea for states. Among other things, the tax is volatile and difficult to forecast, guaranteeing increased instability in state revenue streams.