The median household income rose 4.3 per cent in the year ended June, which means it fell 1 per cent in inflation-adjusted terms.
Over the past three years the median household income rose just 1.4 per cent, while consumer prices over the same period rose 9 per cent.
The figures from Statistics New Zealand's annual income survey covers income from all sources - wages and salaries, self-employment, government transfers and investments - before tax.
Looking at individuals (aged 15 or older) rather than households, the increase in median income in the latest June year was 4 per cent, when the consumers price index rose 5.3 per cent.
Compared with three years earlier, the nominal increase was 2.6 per cent, incomes having fallen between 2009 and last year and stagnated the year before that.
In the latest year wage and salary earners' median income rose 4 per cent (to $800 a week). But only half of that increase was from a higher hourly rate, implying the rest came from working longer hours. The increase in hourly earnings was the lowest for 11 years, Statistics NZ said.
The self-employed continued to go backwards.
Their average weekly income (Statistics NZ does not provide medians at this level of disaggregation) was 2.2 per cent down in the latest year and 10 per cent down on three years ago.
The median weekly income from government transfer payments was up $12 or 4.4 per cent on a year ago, including adjustments to cover the increase in GST, which raised prices by 2 per cent. That group includes superannuitants whose median weekly payments rose 7.6 per cent.
When the income distribution is broken down by gender, ethnicity, age group and educational qualifications, the results are unlikely to surprise.
The odds of a higher income are maximised if someone is a middle-aged male European with a degree.
Living in Wellington also helps. The median income in the capital is 3 per higher than in Auckland and 13 per cent above the national total.
The gender gap among wage and salary earners narrowed, as median hourly earnings for women rose 50c to $19.50 compared with 33c to $21.58 for men. At 9.6 per cent the gender pay gap is now at an all-time low, Women's Affairs Minister Hekia Parata said.
But when income from all sources, not just wages and salaries, is the measure, men are 62 per cent better off at the median and 51 per cent better off on average.
New Zealanders of European descent have a median income 6 per cent above the national total, while Maori are 15 per cent below it, Pacific peoples 29 per cent below and Asians 26 per cent below.
The mid-40s to mid-50s remain the peak earning years.
People with a degree (and a job) have a median income of $1074 a week, 31 per cent above the national total. They make up 23 per cent of the employed population.
Those with no academic or vocational qualifications - 15 per cent of the employed - earn 17 per cent below the national median.
Labour's finance spokesman, David Cunliffe, said the 6 per cent decline in real median income since June 2008 equated to $35 a week in today's dollars.
He said the startling drops reflect that "the abysmal performance of the economy under National has hit poorer Kiwis the hardest". Labour was committed to lifting the minimum wage to $15, making the first $5000 of income tax-free, and removing all GST from fresh fruit and vegetables.