Which of the following statements is incorrect with respect to determining current E & P$?$

a$.$

All tax$-$exempt income should be added back to taxable income.

b$.$

Dividends received deductions should be subtracted from taxable income.

c$.$

Current$-$year charitable contributions in excess of the $10\%$ of taxable income limit should be subtracted from taxable income.

d$.$

Federal income tax refunds should be added back to taxable income.