The Australian Colonies consist of New South Wales, Queensland, South Australia, Tasmania, Victoria & Western Australia. They all produced their own issues before federation in 1901.
Stamps inscribed for the individual States continued in use after federation, until the end of December 1912

On the 1st of March 1901, control of the postal service passed to the federal administration. But it wasn’t until the 13th of October 1910 that the issues of the various States became valid for use throughout Australia.

Postal rates with standardized on the 1st of May 1911.
The first national postage due stamps appeared in July 1902. But it wasn’t until January 1913 that the postage stamps inscribed with ‘Australia’ were issued