Contract terms: duration, cancellation and premiums
Besides benefits, the contract terms matter: duration, notice period, the insurer's right to adjust premiums, health screening and waiting periods. These points decide how flexibly you can switch later. Note that changing supplementary insurance often requires a new health screening. Supplementary insurance falls under the VVG (Insurance Contract Act): insurers may require a health declaration and can refuse applicants, whereas basic insurance (KVG) must accept everyone.