@robtm As the OP is looking at a tax liability considerably larger than the previous year's tax liability and apparently has no more taxes being withheld, (retired), then he MUST make estimated tax payments to avoid an underpayment penalty as the penalty is calculated on a quarter-by-quarter basis. With the bulk of that tax liability arising, (I assume), from the house sale in the second quarter even annualizing the income - putting all of the capital gain into the second quarter - would result in a penalty for the last 3 quarters of the year.
@sportsman2492 If you have no taxes at all being taken out of your retirement checks then you could be underpaid for the 1st quarter in any case. But if you are having taxes withheld then estimate the amount of withholding for the year, subtract that amount from the 2018 tax liability, divide the result by 3, (maybe round up a bit to the hundred's place), and mail those payments in on time.
