This is an announcement for the paper Norming subspaces of Banach spaces” by Vladimir P. Fonf<https://arxiv.org/search?searchtype=author&query=Fonf%2C+V+P>, Sebastian Lajara<https://arxiv.org/search?searchtype=author&query=Lajara%2C+S>, Stanimir Troyanski<https://arxiv.org/search?searchtype=author&query=Troyanski%2C+S>, Clemente Zanco<https://arxiv.org/search?searchtype=author&query=Zanco%2C+C>. Abstract: We show that, if $X$ is a closed subspace of a Banach space $E$ and $Z$ is a closed subspace of $E^*$ such that $Z$ is norming for $X$ and $X$ is total over $Z$ (as well as $X$ is norming for $Z$ and $Z$ is total over $X$), then $X$ and the pre-annihilator of $Z$ are complemented in $E$ whenever $Z$ is $w^*$-closed or $X$ is reflexive. The paper may be downloaded from the archive by web browser from URL https://arxiv.org/abs/1804.09968