The Waitaki District Archives, in Oamaru, now hosts online Oamaru Borough Council rates records from 1880 to 1920 and Waitaki County Council rates records from 1878 to 1900.
Waitaki District Archives curator of archives Christopher Meech said the rates data compiled over more than five years by New Zealand Society of Genealogists Oamaru branch members Amy Winchester, Evelyn McDougall, Barbara Wilde, Beryl Miller, and the late Barbara Pullar represented a "first step" of increasing the digital offerings at the archives.
Oamaru genealogists had voluntarily created many indices, making searching the archives' collections easier, but these were previously accessible only in the archive reading room, during opening hours.
Online searches of historic rates data could show "who's owned the land, what's the description of the land at that time".
"It's one of our primary tools ... for family history, and also property inquiries, when people want to find out about their property," Mr Meech said.
"We might be able to tell when the stables were built, or when a house has been built, or who was occupying it."
However, he said the online index was "an indicative thing" and the records at the archives were the authoritative source.
