Level 15

Investors & landlords

Lets say I have $40,000 of long-term capital gains in Q1 2021, and my federal tax due is exactly $6,000 (i.e. 15% of $40,000).

Then the tax on that gain realized in 2021, as a quarterly tax payment would be due to the IRS by Apr 15th.

Also, lets also say I am a CA resident.

Pretty much the same applies for CA state taxes with the same quarterly due dates as the IRS has for federal taxes. See for more guidance.