The Australian Taxation Office (ATO) web tax filing service is struggling to cope with the EOFY influx.

A huge surge in traffic has ground the ATO's tax filing service to a halt, leading the department to apologise to angry taxpayers.

“We're experiencing some intermittent issues with our online services. We appreciate your patience & recommend that you try again later today,” the ATO posted on Twitter on Wednesday.

“We are still experiencing some systems issues,” the ATO tweeted later that day, “we're working to resolve this as quickly as possible & apologise for any inconvenience.”

But the service remained unfixed on Thursday morning.

“We've worked through the night to implement a system fix. There's still ongoing issues which we're working on. We'll let you know more soon,” the ATO account tweeted.

By late Thursday, the ATO said the service was operating, albeit slowly.

“If you're planning to lodge your own tax return, you have until the 31 October deadline. If you're having trouble getting through we advise waiting 24 hours,” the ATO told new reporters on Thursday evening.