This year's budget could in political terms be seismic. Deciding on a massive tax giveaway to the richest 1% in society and giving £1bn to big business in additional tax breaks they hadn't even asked for, all paid for by pensioners, was the clearest possible indication of who George Osborne thinks is important, politically and socially. As a result, I suspect this budget will be a car crash for him electorally that will impact between now and the next election – as the rebound from some 5 million pensioners, and countless more expecting to retire soon, hits the political landscape.

This is just one in a series of massive errors of judgment by chancellors seeking to make a quick fix who inadvertently commit a major political faux pas. Osborne did it last year with child benefit, and unravelling that has created the most massive tax complexity, despite his commitment to simplicity. Both events undermine his credibility but it's worth recalling that Gordon Brown did this too. Remember the 10p tax fiasco, or his 0% corporation tax rate for small companies? Both were simplifications or apparent giveaways that went badly wrong.

What all these recent political disasters make clear is that tax is core to the political debate; yet despite that, chancellors of all persuasions seem to have no clear understanding of what a strategic tax policy might look like, or of how they can communicate the changes they want to make to our tax system within such a policy framework. This is extraordinary given that elections are pretty much won or lost on the issue of tax.

It's also extraordinary that the only people who have tried to create such a vision of late – the Institute for Fiscal Studies in its Mirrlees review – did so in a way so far removed from the political realities of life that they effectively suggested the abolition of corporation tax and its replacement with what would, for all practical purposes, have been an additional 10% VAT rate. No politician could deliver that, from which point onwards its review was a lost cause.

So what should be happening? For the coalition partners that's an issue they need to take up with the Treasury. For those seeking to replace them, it's another matter altogether. Labour, the Greens and the nationalist parties, all of them in varying degrees on the left of politics, have no choice now but sit down and do the hard work of deciding what they want to achieve with the tax system. That means addressing such issues as who pays and in what proportion; what emphasis is put on direct tax such as income tax or indirect tax such as VAT; what the attitude to business is and what, if any, encouragement is to be given to it; how much is to be invested in tax collection; how tax avoidance is to be addressed; and how tax integrates with benefits. Of course, this overlaps with many policy areas such as equality, housing, employment, pensions, work and the environment.

They also have to work out how they can communicate that vision, not just to their supporters but also to those who will vociferously oppose what they say, whatever the merits of their thinking. That requires "shovel-ready" counter-arguments well in advance of any policy launch. And all these ideas must be ready to go in the first budget after the next election, when there is the best chance of making such change with least electoral impact.

Tax has been the elephant politicians have walked around for far too long. If the left wants to win next time they have to take the issue seriously now. That means, first, investing money in this issue; second, facing up to hard political questions; and third, having a clear vision of what outcomes politicians want – what the politics of the left should be about – and who is meant to benefit from it.

This is, of course, what so many voters are demanding that Labour deliver. They want a clear vision of the future; and in that is also a clear message of what they want Labour to avoid. They don't want Labour delivering tax cuts no one demanded or expected, and they especially don't want politically disastrous 75p increases in state pensions.

If the left can do this before the next election, then that vote is its to take when Osborne's tax vision is now both so plain and so clearly biased to the rich. The question is, will they rise to the challenge?

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