Education loan tax relief for guaranter

No. Repayment of her loan is not giving you relief. Only the borrower can claim the benefits. As far as you are concerned, if you repay the amount, your sister becomes your debtor and she will owe you the money that you paid to discharge her liability. If you are paying the loan without any adequate consideration of fund being repaid to you it is Income from other sources for your sister. However assuming that both of you are siblings and not cousins, you would qualify to be her relative and the amout you repaid to her bank will not be taxed to her if you treat it as a gift.