Determine taxable income in each of the following independent cases. In all cases, the company was formed in $2012,$ was very profitable in all years prior to $2017,$ and had retained earnings of $$1,000,000$ at the end of $2017.$

In $2018,$ Company A has taxable income of $$60,000$ prior to consideration of any net operating loss. In $2017,$ the company incurred a net operating loss of $$10,000.$ It did not elect to waive the carryback period. Determine $2018$ taxable income.

In $2018,$ Company B has taxable income of $$50,000$ prior to consideration of any net operating loss. In $2017,$ the company incurred a net operating loss of $$20,000.$ It elected to waive the carryback period. Determine $2018$ taxable income.

In $2021,$ Company C has taxable income of $$35,000$ prior to consideration of any net operating loss. In $2020,$ the company incurred a net operating loss of $$30,000$ and elected to forgo the carryback period. Determine $2021$ taxable income.

In $2021,$ Company D has taxable income of $$35,000$ prior to consideration of any net operating loss. In $2017,$ the company incurred a net operating loss of $$5,000.$ It elected to waive the carryback period. In $2018,$ the company incurred a net operating loss of $$40,000.$ In $2019$ and $2020$ the company had net income of zero. Determine $2021$ taxable income.