The UBTI had to be paid by the IRA using funds within your IRA, not paid by you personally. The payment from the IRA simply reduces the balance in your IRA, therefore reducing the amount on which taxes will be paid in the future.
If you paid the UBTI personally (which would generally be improper), that would have to be considered to be a regular contribution to your IRA for the year in which the payment was made, subject to the ordinary limitations on IRA contributions.
