  We study the Minimal Supersymmetric Standard Model with Minimal Flavour
Violation for the case of a large parameter tanbeta and arbitrary values of the
supersymmetric mass parameters. We derive several resummation formulae for
tanbeta-enhanced loop corrections, which were previously only known in the
limit of supersymmetric masses far above the electroweak scale. Studying first
the renormalisation-scheme dependence of the resummation formula for the bottom
Yukawa coupling, we clarify the use of the sbottom mixing angle in the
supersymmetric loop factor Delta_b. As a new feature, we find tan-beta-enhanced
loop-induced flavour-changing neutral current (FCNC) couplings of gluinos and
neutralinos which in turn give rise to new effects in the renormalisation of
the Cabibbo-Kobayashi-Maskawa matrix and in FCNC processes of B mesons. For the
chromomagnetic Wilson coefficient C_8, these gluino-squark loops can be of the
same size as the known chargino-squark contribution. We discuss the
phenomenological consequences for the mixing-induced CP asymmetry in B_d -> phi
K_S. We further quote formulae for B_s -> mu^+ mu^- and B_s-B_s-bar mixing
valid beyond the decoupling limit and find a new contribution affecting the
phase of the B_s-B_s-bar mixing amplitude. Our resummed tan-beta-enhanced
effects are cast into Feynman rules permitting an easy implementation in
automatic calculations.
