When property, money, etc passes to a spouse, they don't usually have to pay taxes on anything including real estate or annuities.

Annuities are specifically excluded from the rules that exempt beneficiaries from paying taxes due.

While annuities are an attractive investment at times, because the tax due on the interest is deferred until actually drawn out, it's taxed as ordinary income when drawn out, whether by the owner, the annuitant, or the beneficiary. In addition, if the principal was tax-qualified (that is, if tax was never paid on that money), tax is due on it as well.

The insurance company that issued the annuity knows whether or not tax was paid on the principal; in addition, the annuity's documents should make it clear (the word "qualified" will appear if the annuity is tax-qualified).