With population-based health funding dollars at stake, Southern District Health Board is asking everyone in Otago and Southland to fill in their census forms today.
This year's census is online-based.
Access codes have been sent to every household, and paper forms are also available.
The change has raised concerns many people will either miss out on being counted in today's census, or neglect to take part.
That is of concern to the cash-strapped SDHB, as health funding is allocated according to population.
"Having a sparse population spread over a large area is among our biggest lifestyle attractions but it also puts a lot of strain on the health budget,'' SDHB chief executive Chris Fleming said.
"We need everyone in Otago and Southland to complete their census form so we can stake a claim for every dollar we are entitled to.''
Mr Fleming was particularly concerned numbers in tourist hot spots such as Queenstown and Wanaka were counted accurately.
Health services in both the Lakes District towns have been under strain in recent months.
Lakes District Hospital in Queenstown had issues with a lack of air conditioning during the January heatwave, while Wanaka is about to lose one of its midwives.
"We are a unique region and need everybody to do their bit,'' Mr Fleming said.
"An accurate head-count will help future planning to ensure everyone gets the health services they need.''
