Answer:
a. Is Catherine eligible for the foreign income exclusion for 2020?
Yes
b. Catherine may exclude $45,104 from her gross income for 2020.
Explanation:
In order for Catherine to qualify for the foreign income exclusion, she must have lived in a foreign country for at least 1 one (physical presence test). She lived for more than 1 year if we combine her residence in Germany and Slovenia.
The foreign income exclusion amount for 2020 is $107,600, and Catherine can exclude up to (153 days / 365 days) x $107,600 = $45,103.56 ≈ $45,104.