If trading profit is uneven and hard to cross throughout the quarters, how to estimate the quarterly tax payment then? thx.
The most straight forward method to ensure you avoid the penalty is to pay 100% ( or 110% if your AGI is >75K single or 150K joint) of your prior years total tax owed spread out over 4 quarters. If you end up having a down year you can lower or skip the 4th quarter payment.