Would the level of your IRS Tax fourth stimulus check increase or decrease in round two, or stay the same? Here's what we know and how it could change. When a second stimulus payment is approved, there are a couple of ways the people who qualify might get more money than the first round - and a couple of ways that your total could shrink; We'll explain more below. Knowing The formula the IRS uses to determine the size of your stimulus payment can also be helpful (we find it fascinating). This story is updated regularly.