Labor at its best implements big and bold reforms. We seek a mandate for change. Gough Whitlam was right when he said that Labor sees a mandate as a command to perform, while our opponents see an election win as merely permission to preside.

That impulse to fix problems and make things fairer is what drove Bill Shorten and me to announce a significant package of changes to negative gearing and capital gains tax earlier this week.

There’s been a growing call for some years now to rein in these tax concessions. Groups like Acoss, the Grattan Institute and even ex-Business Council of Australia head Tony Shepherd have pointed out they’re costing the budget billions while directing benefits primarily to those who are already very well off.

If we want to provide needs-based funding to make every Australian school a great one, ensure people with disability have dignified, active lives and keep university accessible for all, then we have to get Australia’s budget into balance.

And if we want to ensure that young people and those on low-to-middle incomes can afford to own their own homes, then we need to change the settings that are currently denying them that opportunity. At the moment, a first homebuyer gets less help from the government than someone buying their second, fifth or tenth property. As progressive policymakers, we can’t let an unfair situation like this stand.

Our plan is bold. First, we will modify negative gearing rules so that the current generous tax benefits can only be claimed for new properties. This will help channel investment into new housing supply which in turn will improve affordability. Creating more demand for new houses will also boost jobs and growth at a time when Australia’s economy is transitioning away from the resources boom.

Treasurer Scott Morrison recently got up in parliament and claimed middle income earners get the bulk of the benefit from our current negative gearing system. By now it’s not surprising that the treasurer should have his facts wrong. But this is yet another occasion when he does.

Data from the Australian Tax Office tells us surgeons get an average tax benefit that is 100 times that received by cleaners and 16 times that of nurses.

Not only do those on lower incomes receive less benefit, but they actually make fewer claims too. The government’s own tax discussion paper shows that less than one in seven Australians earning a middle income claim negative gearing deductions, but almost a quarter of people earning about $250,000 do.

Our plan will also see the existing capital gains tax discount halved to 25%. The current 50% discount is set to cost the budget $8bn by 2018-19. Yet the top 10% of income earners claim 70% of all capital gains. I’d much rather ensure we can continue to fund an adequate pension for those who rely on it than give the wealthiest Australians a tax cut just for buying another investment property.

Of course, when you make changes this significant, it’s important to think about how everyone will be affected. That’s why we’ve decided the new rules will only apply from 1 July 2017. Anyone who already owns an investment property before this date can continue to claim the same deductions they’re eligible for today.

In the past few days we’ve already seen a scare campaign ramping up that will try and shift us from this path. But we will not waver.

That’s because it is our values that have led us here. A belief in fairness, and sharing the tax load equally. A belief in opportunity, and ensuring future generations enjoy the same ones many of us have already benefited from. An understanding that we can’t fund the strong social safety net we care about without getting the budget back under control.

In the face of a government that seems determined to either jack up the GST or slash services to shreds, I’m proud to stand up and say that Labor has found another way. This is a tough call, but it’s the right thing to do. When we’ve made strong decisions guided by our values in the past, we’ve changed this country for the better. I believe this is another of those decisions which define Labor and speak to who we are: as people, as policymakers, and as a movement.