Statistics New Zealand figures showed net migration reached a high of 6100 in the month of March, up from a previous high of 5980.
Annual net migration came close to the 72,000 high predicted to be a peak for New Zealand, in the March year, up from 71,333 in February.
Non-adjusted arrivals fell, driven by a dip in student numbers.
Mr Tuffley said the Reserve Bank was expected to hold its official cash rate at 1.75% for the foreseeable future.
Net migration flows would continue to support overall economic growth, even though the flow was likely to soften over time.
Visitor arrivals growth was easing, implying tourism earnings growth would also soften.
Reviewing immigration figures, Mr Tuffley said a fall in the month's departures was the main driving force for the increase, marking a six-month low of departures in March.
On the other side, the number of arrivals also dipped during the month but the annual total was now not far away from 130,000.
Looking at the composition of arrivals, those coming from the United Kingdom were showing little sign of changing their mind, he said.
''This could be a Brexit-effect, as about 12% of New Zealand arrivals cite the UK as their last residence.''
South Africa was also trending higher, now up to about 4% of arrivals.
There was no major sign yet of an increase in arrivals from the US. There was a small increase in the last few months but nothing far away from recent trends.
Student arrivals had weakened in the past year, particularly from India. Work visa arrivals continued to move higher and accounted for 34% of all arrivals over the last 12 months, a high since the data was first made available in 2004.
Statistics NZ also released its tourism figures and, for the first time since August 2014, annual short-term visitor arrivals did not mark a record high.
However, the dip was only about 600 visitors in 12 months and could be down to the timing of Easter in 2016, which was in March, Mr Tuffley said.
Also, March monthly arrivals were up 1.5%, before the expected boost to come from April's World Masters Games and the June-July British and Irish Lions rugby tour.
