  Aim of this paper is to provide higher order boundary Harnack principles [De
Silva-Savin 15] for elliptic equations in divergence form under Dini type
regularity assumptions on boundaries, coefficients and forcing terms. As it was
proven in [Terracini-Tortone-Vita 22], the ratio $v/u$ of two solutions
vanishing on a common portion $\Gamma$ of a regular boundary solves a
degenerate elliptic equation whose coefficients behave as $u^2$ at $\Gamma$.
Hence, for any $k\geq 1$ we provide $C^k$ estimates for solutions to the
auxiliary degenerate equation under double Dini conditions, actually for
general powers of the weight $a>-1$, and we imply $C^k$ estimates for the ratio
$v/u$ under triple Dini conditions, as a corollary in the case $a=2$.
