Del. Code tit. 25, § 5315

Any tax laid upon lands or tenements according to law which is paid by or levied from the tenant of such lands or tenements, or a person occupying and having charge of same, shall be a setoff against the rent or other demand of the owner for the use, or profits, of such premises. If there is no rent or other demand sufficient to cover the sum so paid or levied, the tenant or other person may demand and recover the same from the owner, with costs. This provision shall not affect any contract between the landlord and tenant.