Elaine died on May 1, 2020. Her gross estate consisted of the following items:
Cash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  $ 40,000
Stocks traded on a stock exchange . . . . . . . . . . . . . . . . . . .  4,200,000
Personal residence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,550,000
25% capital interest in a 60-person partnership . . . . . . . .  6,400,000

Elaine’s Sec. 2053 deductions totaled $200,000. She had no other deductions.

a. What percentage of Elaine’s federal estate taxes can be paid in installments under Sec. 6166? When is the first installment payment due?

b. Could Elaine’s estate elect Sec. 6166 treatment if the stocks were valued at $10.2 million instead of $4.2 million?