Appleton Corporation, a U.S. corporation, reported a total taxable income of $8,000,000 in 2020 and pre-credit income taxes of $1,680,000. The taxable income included $2,000,000 of foreign source taxable income from the company's branch operations in the United Kingdom. All of the branch income is foreign branch income. Appleton paid U.K. income taxes of $500,000 on its branch income. In addition, Appleton's taxable income includes royalties of $400,000, classified as foreign passive income. Appleton has foreign taxes withheld of $40,000.

a. Compute Appleton's net U.S. tax liability

b. Compute any foreign tax credit carryover available for 2021.