Federal election campaign tensions rose to the surface as Scott Morrison and Bill Shorten locked horns in a second leaders' debate in Brisbane, with the Labor leader accusing the Prime Minister of invading his personal space.

Key points: Scott Morrison and Bill Shorten clashed over the issue of tax in their second leaders' debate

Scott Morrison and Bill Shorten clashed over the issue of tax in their second leaders' debate Mr Morrison criticised Labor's plan to scrap franking credits, while Mr Shorten accused the PM of not doing enough to crack down on multinational tax avoidance

Mr Morrison criticised Labor's plan to scrap franking credits, while Mr Shorten accused the PM of not doing enough to crack down on multinational tax avoidance Other topics were mental health, religion, climate change and education

"You're a classic space invader," Mr Shorten told Mr Morrison as the PM leaned in to make a point in a debate over tax policy.

The debate in front of 100 people at the Gabba came after a day in which the parties both lost candidates to dodgy social media history.

In an at-times tense exchange hosted by David Speers on Sky News, Mr Morrison and Mr Shorten took each other to task on tax plans, mental health, education, religious freedom and climate change.

Questioners took turns to ask the leaders what solutions their respective governments could offer.

The leaders were competing for whose policy was more sensibly costed and adequately spent from the first question, on how to address the low rate of convictions for sexual assaults in Australia.

While Mr Morrison and Mr Shorten agreed on the need to focus resources on policing and family violence services, the Labor leader argued his party would go further than the Coalition's plan for frontline services.

The leaders fielded multiple questions on mental health, which Mr Morrison described as Australia's "real crisis", with both men pledging to dedicate serious money towards improving.

But it was, of course, on the issue of tax that the two leaders butted heads the most.

On a question about Labor's policies and costings, Mr Morrison took another opportunity to describe the pledge to scrap franking credit cash refunds for people who do not pay income tax as a tax on retirees.

But Mr Shorten rejected that and instead attacked Mr Morrison for not doing enough to crack down on multinational tax avoidance.

When it came time to make the final pitches to the voting audience (and those watching from home), Mr Shorten promising a "time for change" to a "united, stable government" while Mr Morrison urged people to stick with the economic managers they know.

There are requests in for a third debate at some point next week, but the leaders are yet to commit.

Look back over our live blog below.