What's exasperating right now is the suspicion of what this Government will get away with it if it decides to break its promise over the bright-line test.
I think if it extends it beyond five years, despite only three months ago promising it wouldn't, that broken promise will probably be ignored.
I find that so hard to stomach, because is that how easily we tolerate a complete lack of integrity.
Three months - Grant Robertson could not have been clearer.
On September 9 he released Labour's election tax policy and all it was 39 per cent income tax on income over $180,000.
And we all looked at that and thought, that can't be it: Labour loves tax surely it's planning more.
So in an interview that day, I asked him about all the taxes we could think of, because we wanted to be sure that if you voted for Labour, you knew exactly what it was going to do.
And so I asked whether he would change the bright-line test. He said no.
I checked: he wouldn't change the rate or the years? He said no.
And yet, here we are three months on, and he's considering doing exactly what he promised he wouldn't.
He has written to the Treasury asking for advice on what would happen if he extended the very bright-line test he promised he wouldn't extend.
Robertson told me that the country is "faced with a situation where even between September and October we're facing a rapid increase in house prices", and this is one of the things the Government is "taking a look at".
I think the only reason he's done that is because he also suspects he can get away with it.
Maybe because Labour's Covid-response halo means it can do no wrong in the eyes of some.
Maybe because - faced with the excuse that the housing market is "out of control" - people might think a broken promise on something they may not have to confront is not a big deal.
But the fact is, this is about integrity. Robertson cannot claim that things have changed from September because of Covid. Covid was a thing in September, the housing market was already hot.
That very week, the Real Institute declared Auckland and New Zealand house prices were "at an all-time high" - it was all over the news.
The only thing that has changed is an election.
Robertson made the promise before the election to fight off National's claims that Labour would find a way to tax us, and to make sure voters had fewer reasons to avoid Labour.
Post-election, that's not a worry now. The votes are in the bank.
Robertson still has a chance to back away from this. By writing to Treasury, he's cleared the ground to do it, he's flown the kite, and he's signalled this loud and clear.
But he can still decide not to do it. He must keep his promise. It's a matter of integrity.
If he breaks it, he might get away with it politically for now, but in the future, his word will count for so much less.