What do you mean? As said, it depends on your PCB board stack-up as the space is based on dielectric. If you mean the space b/w TX/RX, it is as below info.
TX and RX should not be routed on the same layer. If this is required in a design, they should not be interleaved, and the spacing between the closest RX and TX lanes must be 9x Dielectric height spacing.