Adrian's taxable income (from wages and investments) is $100,000 in 2017/18. He retired from employment in December 2017 and received a gratuity (an employment termination payment) of $50,000. The payment is not an excluded payment so that the lesser of the ETP cap and whole-of income cap applies for the purposes of determining the ETP tax offset. How much of Adrian's ETP is eligible for the ETP tax offset