Sorry about your personal loss. The inheritance isn’t taxable, but receiving funds from the annuity is because your cousin never paid tax on this income. Sounds confusing, but it’s the same thing when inheriting an IRA—receiving the inheritance isn’t taxable but when distributions from the account are taken, the distributions become taxable. Unlike property that gets a stepped-up basis when the owner dies so that appreciation is never taxed, there is no similar rule for ordinary income; it remains taxable to heirs and beneficiaries.
A 12-month period ending on the last day of any month other than December. Partnerships, S corporations, and personal service corporations are limited in their choice of fiscal years and face special restrictions.