If the trust provides that the trustee will follow the Uniform Principal and Income Act, then I believe Section 16361 would apply. And more specifically section 16361(c).

You can see the UPIA at http://www.calcpaweb.org/la/estate/prin_inc.html Cursor down to Sec 16361.

This section seems to indicate that there is no income until the trustee starts drawing from the variable annuity, and then, only if the withdrawals are required. And then, only 10% is income and 90% is principal.

And if that result seems bizarre to you, you're not alone!

The UPIA also includes a "power to adjust", at Sec 16336.