Tachyon condensation and universality of DBI action

We show that a low-energy action for massless fluctuations around a tachyon ic soliton background representing a codimension one D-brane coincides with the Dirac-Born-Infeld action. The scalar modes which describe transverse o scillations of the D-brane are translational collective coordinates of the soliton. The appearance of the DBI action is a universal feature independen t of details of a tachyon effective action, provided it has the structure i mplied by the open string sigma model partition function.