Planar-Toroidal Decomposition of $K_{12}$

In 1978, Anderson and White asked whether there is a decomposition of $K_{12}$ into two graphs, one planar and one toroidal. Using theoretical arguments and a computer search of all maximal planar graphs of order 12, we show that no such decomposition exists. We further show that if $G$ is planar of order 12 and $H\subseteq \bar{G}$ is toroidal, then $H$ has at least two fewer edges than $\bar{G}$. A computer search found all 123 unique pairs $(G,H)$ that make this an equality.