No delay to 2017 returns: tax office boss

Tax commissioner Chris Jordan has dismissed as "completely without foundation" claims his office won't be able to handle this year's tax returns because of recent system outages.

He is "absolutely confident" taxpayers will be able to lodge their returns and receive refunds on time from July 1.

"It is disappointing that some people are trying to create unnecessary mischief during what has already been a challenging and testing time for the community and the ATO," Mr Jordan said in a statement on Wednesday.