What are Effective Marginal Tax Rates?
This post is by PaulL, a regular commentor and occasional contributor. It is the second post in a series on the financial incentives to work and the impacts of our tax and transfer system on household formation. The index to all posts in the series can be found here.
When we talk about incentives to work what matters is the impact on the next dollar – the impact at the margin. People care about the impact of the change from their previous situation. I wasn’t working and now I am. How much extra money do I get than I had before? I was working 20 hours a week, now I’m working 24 hours. How much extra money do I get?
At a headline level the lowest marginal tax rate in NZ is 14%. So if I work four extra hours at minimum wage, I should get $21.20 x 4 hours x 86% = $73 cash in the hand. Easy, right?
But remember that I’m getting a benefit. I may be getting an accommodation supplement. I may be getting childcare support, and I get tax credits via working for families. All those government programmes have some form of threshold and abatement rate.
If I work an extra hour I get $21.20 gross income.
- I lose $3 to tax.
- If I’m over the $160 weekly income threshold, my jobseeker benefit will also be reduced by 70 cents in the dollar. I lose another $14 in benefit reduction.
- I may also have accommodation supplement. If I cross the earning threshold I’ll lose 25 cents in the dollar.
- If I’m a parent I’m probably getting Family Tax Credit. I’ll lose 27 cents in the dollar if my household income is more than $33,000 per annum.
- If I’m not getting a main benefit I may get In Work Tax Credit, and I’ll lose 27 cents in the dollar on that
- If I’m a sole parent I’ll be getting a subsidy on my childcare. That has income thresholds at $840 a week, $1,250 a week, $1,400 and $1,500 a week, each of which reduce the amount paid.

