Dr Tagg, originally from Yorkshire, is eligible to pay interest of up to 6.2% on his loan which was taken out with Student Finance England.
He estimates in this tax year alone, he has accumulated an extra £3,000 of debt, but only paid off half of that.
Interest is calculated differently depending on when and where you took the loan out which UK chancellor Rachel Reeves called a “fair and reasonable” system, after backlash for freezing the threshold in England.
But Dr Tagg said “It wasn’t something that was at the forefront of my mind” when he started a five-year course at Cardiff University when he was 18.
“Like most 18 year olds, I saw university as furthering your education, a chance to better yourself,” he said.
“I was aware that the university fees had increased at the time, and I think they’d gone from £3,000 to £9,000 there, so I did know I was going to be borrowing significantly more.
“What I wasn’t prepared for, because I didn’t have a crystal ball, was how that would spiral, I’d accumulated another £14,000 worth of interest before I’d even finished my studies.”