Blackmore is testifying before the Tax Court of Canada, disputing the government's assertion that he must add an extra $1.5 million to his income from 2000 to 2004 and in 2006.
On Tuesday, Blackmore told the court he has 21 wives, but he mentioned eight or nine of them have left him.
"These are pretty much who have lived with me as wives," he said. "I've had lots of other people in my life who are not considered wives."
When asked by federal government lawyer Lynn Burch about the number of children he has, Blackmore didn't want to go by memory.
"In order for me to make an accurate list I would need some time to do that."
He acknowledged having 47 children between 2000 and 2006 and said he also has 20 grown children from marriages that date back to 1975. Seven of those children are from his first, legal marriage to Jane Blackmore. She later divorced him.
During the period in question for tax purposes, Blackmore testified he didn't live with any of his wives. Instead he lived in the basement of a home while his ailing mother lived upstairs.
Residents of Bountiful, in southeast B.C. on the Canada, U.S. border, follow the Fundamentalist Church of Jesus Christ of Latter-Day Saints, an offshoot of the Mormon church.
Mormons renounced polygamy more than 100 years ago, but Blackmore said he follows the principles set out by church founder Joseph Smith, including plural marriage.
Blackmore explained to the court that they believe in plural marriage because God once was a man and that means He is everyone's common father.
"It is our aspiration of becoming like He is, we need to do what has been taught," Blackmore explained.
There is nothing in their faith that says they need to have many children, Blackmore said.
He agreed that some of the boys in the community have left, but said it wasn't because there weren't enough wives to go around.
"Some may have left out of frustration. They wanted to try some drinking and that's not a part of our life," he said. "One boy wanted to try weed."
Blackmore told the judge he's able to support himself and his large family with the meagre income he claimed on his tax forms because his community is almost self sufficient.
In one audit year, Blackmore and the three other directors of his company, J.R. Blackmore and Sons Ltd., claimed income ranging from $15,000 to $45,000 each.
An audit report by the Canada Revenue Agency said Blackmore couldn't support his large family with that kind of income.
Blackmore's lawyer David Davies asked him if his small income was enough to support his current family.
"In my view it is, considering all the basic staples that are provided," he told the trial.
Blackmore spent much of the day explaining to the court how his community grows and shares food, everything from fruit and corn to potatoes and tomatoes grown in a large garden.
Potatoes and other root vegetables are stored in cellars around the community and everyone has access to food, Blackmore told the court.
"There was and is a general exchange of food if anyone runs out."
He said the community has three commercial-style freezers that are filled with beef raised by the community, wild game shot by the men and chickens gained from a neighbour for an exchange of labour.
Blackmore said they have an agreement for 10,000 chickens a year and in return, community members clean the chicken barns.
"It fit for our community, we are able to provide a huge supply of chicken for every member."
Women and children process the chickens, he testified.
"I actually started plucking chickens in school."
The community also has 10 milk cows and its own milk bottling system.
Blackmore's testimony was meant to shore up his claim that he and his followers are a religious congregation where the resources are shared and everyone works for the benefit of the entire community.
He claims his income should be spread over all the community residents, similar to the tax laws that govern religious groups such as Hutterite colonies. Those residents have no property or possessions and work only for the community.
Blackmore told the judge that midwives who earn extra money outside of Bountiful are expected to tithe the funds.
"They use the money they earned for the good of the community," Blackmore told the court.
Blackmore's company has several sectors involving logging, fence-post manufacturing and farming in B.C., Alberta and Idaho.
He told the court he pays his employees, all of whom are community members, only enough for what they need.
"We had to do it that way or we'd have one person sitting there and doling out money every day," he said.
Anything they have that is extra would be expected to be tithed back, in keeping with the early practices of the Mormon church, Blackmore said.