A tax ruling which could have saved thousands of bus commuters hundreds of dollars a year in public transport costs was left unused by the government for so long, it has expired.

The government achieved a tax ruling, which would have allowed public servants on the TransLink network to salary sacrifice their bus travel to and from work, in 2010.

It became applicable from April, 2011, but expired in March this year, without ever having been used, despite other networks including Victoria's Myki's commuter club, allowing for salary sacrificed travel for eligible commuters as early as 2013.

Queensland has not been able to find a "technical solution" to offer the same service, with the government now having to re-apply for the right to do so, when it manages to roll out its own cards.