"Winning $13m is a real privilege and we feel so fortunate."
Lotto NZ said the couple are among 750 Kiwis who have won $1m or more since the lottery began in 1987.
The largest prize this year was a whopping $22.2m Powerball prize won by an Ashburton couple in April.
Last night's $18m prize wasn't struck so is expected to be upwards of $20m next week.
Figures released by Lotto NZ showed that in the year to June, 17 Kiwis had become instant millionaires.
Sixty-five per cent of the winners splashed out on food and wine after they won, buying coffee and cakes, champagne and dinners.
Forty per cent paid off their mortgage or bought a home, 50 per cent went overseas, 20 per cent splashed out on a new car and 20 per cent indulged in their hobbies.