OLYMPIA (AP) — House Democrats unveiled a two-year state budget proposal that seeks $1.4 billion in new revenue, including a new capital gains tax on the sale of high-value stocks and bonds.

The $52.8 billion proposal, released Monday, increases spending in several sectors of state government, including K-12 education and the state’s mental health system.

The main portion of the plan seeks to levy a 9.9 percent capital gains tax on earnings from the sale of stocks, bonds and other assets above $100,000 for individuals and $200,000 for those who file jointly.

Opponents of a capital gain tax have argued that it’s a type of income tax illegal under state law; supporters call it an excise tax. The debate is certain to end up in court if the Legislature approves the tax.