More than half of all Kiwis living overseas with a student loan are dragging their feet on paying their debts.

And the amount of money the taxman considers overdue by those living overseas has jumped by almost $150 million in the space of just a year.

Inland Revenue has blamed "economic and political uncertainty" for the spike in overdue payments.

But Revenue Minister Stuart Nash has warned those falling behind on payments not to "bury your head in the sand".

It comes as a Kiwi living in the United Kingdom says she's a student loan exile - unable to come home to take care of her mother because she fears being arrested at the border.

The woman estimates her student loan is now more than $100,000.

She blocked contact from Inland Revenue about five years ago, saying attempts to organise affordable repayments had failed and the stress was overwhelming her.

"They were really like loan sharks, like Repo men in their approach. When they say, 'Let's work something out', what I'm saying is, 'I've heard that before, where they sound all nice and supportive about it.' But that's not how it's like in reality."

The woman, who asked not to be identified, had been back to New Zealand twice, once when her father died and she helped her mother move home.

News of another student loan defaulter being arrested at Auckland Airport this month, which the Herald reported yesterday, had left her more convinced she couldn't come home.

• Student loan exile: 'Mum is going to die and I'm not going to be there'

"My mother has always been sick, and I had to help her move. I was terrified the whole time that I would be arrested, and I haven't been back since ... I just accepted a long time ago that probably my mum is going to die pretty soon, and I'm just not going to be there."

She understood many New Zealanders would not be sympathetic, and said some of her own relatives were in the same camp. However, she urged politicians and officials to find a solution for people in her position.

Figures, obtained under the Official Information Act, reveal that as of October last year, the total amount of student loan debt from borrowers based overseas was $3.5 billion.

Inland Revenue data shows the total value of all student loans on the Government's books is $16b – meaning 20 per cent of all loans are held by people living overseas.

And, according to recently released student loan data, 54 per cent of overseas-based borrowers are not taking "positive actions" towards repaying their student loan.

This includes not talking to the IRD about the debt, making payment arrangements to pay the debt off or avoiding paying altogether.

Of the $1.5b worth of debt that IRD considers overdue, more than 90 per cent is owed by those living outside New Zealand.

Act leader David Seymour said he had no sympathy for those who are "ripping off" ordinary New Zealanders by not paying back their student loans.

"They have borrowed from a very generous scheme and have gone to some of the best [universities] in the world."

National's Tertiary Education spokesman, Shane Reti, said Kiwis living overseas have a responsibility to pay back their loans.

Seymour said he fully supported loan defaulters being arrested at the border – "they don't deserve a free ride."

But Nash said the arrest of student loan defaulters at the border is used as a very last resort.

"It's only used after IRD has made every attempt to contact the borrower and get them back on track with a plan that works for all parties."

The new student loan data shows the amount of overseas loan debt the IRD considers overdue has been increasing rapidly.

In the year to June 2017, $1.107b was marked overdue – that increased to $1.205b the following year.

That figure was $1.4b as of June last year – a 12 per cent jump which works out to be a $144m increase.

This dwarfs the total value of New Zealand-based individuals' overdue loan payments, which was $132m in the year to June 2019.

The sharp increase is despite the number of former students living overseas only increasing by 0.7 per cent over the same period.

Student loans are interest-free if the borrower lives and pays off their loan while living in New Zealand and it's automatically deducted from the borrower's salary.

But, if the borrower is outside of the country for more than six months, the IRD charges interest on the loan and they have to manage their own repayments to IRD.

IRD said there were a number of factors which had led to the reduction in overseas-based borrower repayments.

"[These include] aged default being more difficult to collect, and economic and political uncertainty in countries borrowers reside in."

Many former Kiwi students live in the UK which is currently in the process of a lengthy and complicated divorce from the European Union.

The IRD report also said some of its staff have been temporarily assigned to its Business Transformation Programme and this could have impacted the debt collection figure.

Nash said the IRD works hard to get in touch with borrowers living overseas to make sure they're aware of their obligations to repay their loans.

"If any borrower is concerned, the best piece of advice is to get in touch with IRD to work through options – don't bury your head in the sand."

- additional reporting Nicholas Jones