Accurate equation of state of AuIn₂was obtained by x-ray diffraction measurements with ELETTRA synchrotron source to pressures over 20 GPa. Below 5 GPa, the P-V data when transformed to universal equation of state (UEOS), shows a deviation from linearity, confirming an electronic transition,consistent with the anomaly observed earlier in fusion and electrical data. The present high-resolution data also reaffirm a structural phase transition beyond 9 GPa. Full potential electronic band-structure calculations reveal a Lifshitz transition at the observed anomaly in the UEOS. Its transition pressure was found to be sensitive to the exchange-correlation terms.