How much do I have to pay estimated taxes for 2021?

[Tahoe_NV]

My 2021 income from work has decreased around 30% compared to 2020, but in 2021 I took huge profits from stock trading compared to 2020. 

Therefore, my current withholding has decreased in 2021, but expected taxable income would be much higher in 2021 compared to 2020.

I have plan to make an estimated tax payment, and here are questions for how much I should pay.

1) Should I pay the difference between the expected 2021 tax withholding from my paycheck and 2021 expected tax?

2) May I pay just the difference between the expected 2021 tax withholding from my paycheck and 110% of actual 2020 taxes?

If I choose option 2, there is huge difference from 2021 expected tax, so I am worried I may have tax penalty due to too little tax withholdings in 2021.

[DanPaul02]

To avoid an underpayment penalty:

• Owe less than $1000
• Paid at least 90% of tax for 2021
• Paid 100% of the tax on the return for 2020