We consider a Lévy-driven tandem queue with an intermediate input assuming that its buffer content process obtained by a reflection mapping has the stationary distribution. For this queue, no closed form formula is known, not only for its distribution but also for the corresponding transform. In this paper, we consider only light-tailed inputs. For the Brownian input case, we derive exact tail asymptotics for the marginal stationary distribution of the second buffer content, while weaker asymptotic results are obtained for the general Lévy input case. The results generalize those of Lieshout and Mandjes from the recent papers (Lieshout and Mandjes in Math. Methods Oper. Res. 66:275-298, 2007 and Queueing Syst. 60:203-226, 2008) for the corresponding tandem queue without an intermediate input.Keywords Brownian tandem queue · Levy driven tandem queue · Intermediate input · Two dimensional semi-martingale reflected process · Stationary buffer content · Exact tail asymptotics · Tail decay rate · Large deviations Mathematics Subject Classification (2000) 60K25 · 68M20 · 90B15