This bill introduces a new provision to chapter 82.87 RCW, allowing taxpayers to prepay their capital gains taxes up to six months before the due date for filing and payment. Taxpayers can submit these payments in the manner and form prescribed by the department, providing them with greater flexibility in managing their tax obligations.

Additionally, the bill stipulates that if a taxpayer overpays their taxes for the taxable year, the department cannot assess interest for the period before the due date. This provision aims to protect taxpayers from incurring additional costs due to overpayment, ensuring that they are entitled to a remittance without penalty.