The HCOOH molecule represents the simplest organic acid which is also supposed to play a role in the interstellar formation of more complicated biomolecules. Its interaction with slow electrons in the gas phase is analysed in the present work with the view of providing specific structural and dynamical information on those resonant states which lead to different transient negative ions (TNIs) formation. The latter resonant states in turn guide molecular fragmentation along different pathways, forming HCOO−, O− and OH− fragments as experimentally observed. The present calculations, carried out at the equilibrium molecular geometry, indeed support the presence of two main resonances within the expected energy range and further indicate the presence of antibonding nodal planes in the excess electron resonant wave function features which could explain the observed fragmentation products formed during the subsequent dissociative break-up.