Otago and Southland district health boards regional chief finance officer Robert Mackway-Jones said Otago historically had written off low levels of debt, but that was changing.
Last financial year, it wrote off $20,561, all of it related to non-residents.
This compares with a total of $61,000 for the previous five years, when the yearly amounts ranged from $1000 (2007) to $21,000 (2006).
Southland also wrote off about $21,000 overall last financial year, $6000 of that related to overseas patients.
Both boards had to increase provision for doubtful debts, Otago allocating $310,000 in its budget, with the bulk expected to be for non-residential debt ($262,000), he said.
In Southland, the debt provision was $167,000, with non-residential debt expected to be half that.
Mr Mackway-Jones said he thought more could be done to identify people with chronic conditions before they entered the country.
Most costs incurred by visitors were from acute problems and typically involved surgery, specialist care and intensive care.
While both boards were "nowhere near" the levels of debt incurred by Auckland hospitals, "we are certainly noticing it becoming an increasing problem", Mr Mackway-Jones said.
Last financial year, the Otago board received $758,759 for the care of non-resident patients.
Southland received almost $400,000.
