He’ll Sell the Rental in June and Owe the IRS $90,000 in April. He’ll Send Them Exactly What He Paid Last Year, in Four Installments, and the Penalty on the Rest Will Be Zero

Selling a rental property mid-year may trigger a substantial tax bill, but the article says the penalty calculation is not based on the size of the gain. It points readers to a single line on the prior year’s tax return, without identifying that line or giving a penalty amount.