Simple answer: you can wait and pay when you file your tax return, if you normally get a refund.
You should make estimated tax payments for the current tax year if both
of the following apply:
- 1. You expect to owe at least $1,000 in tax for
the current tax year, after subtracting your withholding and credits.
- 2. You expect your withholding and credits to be
less than the smaller of: 90% of the tax to be shown on your current year’s tax
return, or 100% of the tax shown on your prior year’s tax return.
(Your prior year tax return must cover all 12 months.)
There is no underpayment penalty, if you meet these rules.
The amount of tax could be quite small. Long term capital gains (LTCG) are taxed at 0% until your total income reaches the 22% tax bracket, Then LTCG are taxed at 15%. But, a portion of your gain is "deprecation recapture", which is taxed as ordinary income, but no more than 25%.
If you decide to make an estimated payment, it is not due until Jan. 15, 2019, because the extra income was received in the 4th quarter of 2018.
