you provided no information so whether estimated taxes should have been paid is unknown.
there are no underpayment of estimated tax penalties for 2021 if:
1) withholding and timely estimated tax payments are at least 90% of your 2021 tax or
2) you owe less than $1,000 after subtracting your withholding taxes (but not estimated tax payments) from 90% of your 2021 tax or
3) withholding and timely estimated tax payments are 100% of your 2020 tax (110% if your 2020 adjusted gross income was more than $150,000)
if you owned and lived in the house for 2 or more years in the last 5 years before sale $250,000 of gain is tax-exempt ($500,000 if you are married on the date of sale and your spouse also lived in the house for 2 years in the last 5). this assumes the house was never a rental while you (or your spouse, if married) owned it. even if the 2-year tests are not met you may be entitled to a partial exclusion if the reason for selling is a change of job location (certain criteria have to be met), or for specific health reasons other than your general health or well-being (for yourself or almost any member of your family living with you) and finally unforeseen circumstances -
(e)(1) In general. A sale or exchange is by reason of unforeseen circumstances if the primary reason for the sale or exchange is the occurrence of an event that the taxpayer could not reasonably have anticipated before purchasing and occupying the residence. A sale or exchange by reason of unforeseen circumstances (other than a sale or exchange deemed to be by reason of unforeseen circumstances under paragraph (e)(2) or (3) of this section) does not qualify for the reduced maximum exclusion if the primary reason for the sale or exchange is a preference for a different residence or an improvement in financial circumstances.
(e)(2) Specific event safe harbors. A sale or exchange is deemed to be by reason of unforeseen circumstances (within the meaning of paragraph (e)(1) of this section) if any of the events specified in paragraphs (e)(2)(i) through (iii) of this section occur during the period of the taxpayer's ownership and use of the residence as the taxpayer's principal residence:
(i) The involuntary conversion of the residence.
(ii) Natural or man-made disasters or acts of war or terrorism resulting in a casualty to the residence (without regard to deductibility under section 165(h)).
(iii) In the case of a qualified individual described in paragraph (f) of this section -
(A) Death;
(B) The cessation of employment as a result of which the qualified individual is eligible for unemployment compensation (as defined in section 85(b));
(C) A change in employment or self-employment status that results in the taxpayer's inability to pay housing costs and reasonable basic living expenses for the taxpayer's household (including amounts for food, clothing, medical expenses, taxes, transportation, court-ordered payments, and expenses reasonably necessary to the production of income, but not for the maintenance of an affluent or luxurious standard of living);
(D) Divorce or legal separation under a decree of divorce or separate maintenance; or
(E) Multiple births resulting from the same pregnancy.
(3) Designation of additional events as unforeseen circumstances. The Commissioner may designate other events or situations as unforeseen circumstances in published guidance of general applicability and may issue rulings addressed to specific taxpayers identifying other events or situations as unforeseen circumstances with regard to those taxpayers (see § 601.601(d)(2) of this chapter).
