A fuel cell system includes a plurality of solid oxide fuel cells arranged in a fuel cell stack, an integrated heat exchanger/reformer operable to partially reform an anode feed prior to entry into the fuel cell stack, an anode tailgas oxidizer, and an offgas flow path extending away from an anode side of the fuel cell stack and having a first branch to selectively combine offgas from the anode side of the fuel cell stack with fuel from a fuel source to comprise the anode feed to the fuel cell stack and a second branch to supply offgas from the anode side of the fuel cell stack to the anode tailgas oxidizer. The integrated heat exchanger/reformer transfers heat from the oxidized offgas from the anode tailgas oxidizer to the anode feed before the anode feed enters the anode side of the fuel cell stack. The offgas from the anode tailgas oxidizer provides the sole heat source for the anode feed traveling through the integrated heat exchanger/reformer.