"Actual services delivered out of district are generally low-volume, highly specialised cases in terms of elective work," he said.
Certain types of treatment were not offered in the Bay of Plenty, including neurosurgery and paediatric surgery.
Included in the $70m was treatment for Bay of Plenty residents at hospitals outside the region when they were away from home.
"It makes more sense to treat the person at the nearest hospital when time is of the essence, rather than bring them back to Bay of Plenty," Mr Everitt said.
Labour health spokesman David Clark said the inter-DHB payment system needed a "full and broad-ranging review into funding".
He said smaller health boards were disadvantaged by extra administrative costs under the current system.
A national price for services was agreed on by all health boards for treatment of patients from other health board areas, but the Bay of Plenty was still losing out.
The revenue from other health boards into the Bay of Plenty was far less than the money paid out - less than $16m in the year to June.
Payments to other health boards for patient treatment varied widely between regions.
Whanganui, which has a much smaller population than the Bay of Plenty, paid $35m to other health boards and received only $7m.
Whanganui District Health Board chief executive Julie Patterson last month said there was a problem with visitors from out of town not giving their home addresses.
Mr Everitt said giving temporary addresses was not an issue, however, as a national database listed patients' home addresses.
The Bay of Plenty District Health Board had a deficit of more than $1m for the last financial year.
Health Minister Jonathan Coleman announced a funding increase of $32m for the Bay of Plenty in May last year, taking total government funding to $718m.
The nearby Lakes District Health Board paid $28m to other boards in the last financial year, and received $19m.