[19 February 2018] Stuff reports today on planned steep rates rises if the Horowhenua District Council goes ahead with new drinking water and wastewater infrastructure plans:
Steep rates increases are on the cards for Horowhenua, with annual rises of more than 6 per cent for the next few years.
The costly hit on homeowners is revealed in the Horowhenua District Council’s draft Long-Term Plan for 2018-2038.
It says the proposed rates increase for 2018/19 is 6.53 per cent.
Increases peak in 2021/22, at an expected 6.42 per cent.
By 2023/24, the increase is expected to soften to 2.91 per cent.…
Meanwhile, Horowhenua may lose its community halls and spend millions on new drinking water and wastewater infrastructure.…
A plan for new drinking water and wastewater infrastructure in Hokio Beach, Manakau, Εhau, Waikawa Beach and WaitΔrere Beach could cost the council $108m. …
Horowhenua rates rises expected to peak in in 2021/22 | Stuff.co.nz

A quick spreadsheet shows that using the information above (and making some assumptions about when and how the increase reduces), for every $1000 of rates this year by 2023 we could be paying at least $1338.
Your maths is not correct.
You have applied 6% accumulative over each of 5 years.
The correct figure is $1,276, which is a total 27.5% increase over 5 years.
Thanks. Always happy to have my maths challenged. I did reduce the last 2 years to 4% and 3% to reflect the drop mentioned in the article.
It could also be the case that I *intended* to make those last 2 columns 4% and 3%, but didn’t in fact do thatβ¦