A microfluidic test carrier having a substrate, covering layer, and capillary structure formed in the substrate is provided. The capillary structure is enclosed by the substrate and covering layer and comprises a receiving chamber, sample chamber and connection channel between the receiving and sample chambers. The receiving chamber has two boundary surfaces and a side wall, wherein one boundary surface forms the bottom and the other forms the cover. The receiving chamber has a surrounding venting channel and dam between the receiving chamber and venting channel. The dam and venting channel form a capillary stop configured as a geometric valve, through which air from the receiving chamber can escape into the venting channel. The connecting channel between the venting channel outflow and sample chamber inflow controls fluid transport from the receiving chamber into the sample chamber. The capillary stop is configured to prevent autonomous fluid transport from the receiving chamber.