Mark and his wife divorced in 2016. Mark pays alimony and child support to his former spouse. He is required to pay $6,000 in child support and $10,000 in alimony a year. At the beginning of the current year, he is in arrears for child support in the amount of $12,000 and alimony in the amount of $20,000. During the current year, he starts to catch up and pays $25,000. How much is deductible alimony for the current year?