Hammond's comments highlight Brexit divisions
It is traditionally the job of a chancellor to look after the nation's money, not to be flash with taxpayers' cash, to balance the books, and not to go around making promises that can't be paid for.
And in normal times under Conservative governments there is usually customary support from the backbenches for them to err on the side of caution when it comes to controlling the purse strings.
But there is very visible anger from some Tory quarters today about Philip Hammond's approach to spending when it comes to making preparations for life outside the EU. Why?
Well, how much to spend on preparing for leaving the EU without a deal, and when to spend it, has become the new faultline in the Tories' never ending divisions over Brexit.
The chancellor wrote in the Times this morning that he'd only be prepared to spend money when it was necessary and not in next month's Budget.
And he went even further in front of MPs this morning, saying that he wouldn't spend until the "very last moment".
That is a direct challenge to some Brexiteers who have been pushing for billions to be spent now, yes, to be ready just in case, but also in order to demonstrate to Brussels that the threat to walk away is a real one.
And two different cabinet sources say his comments today come on top of a row at cabinet yesterday over precisely this issue, an exchange described as "robust".
Number 10 acknowledges that there was a brief discussion of the preparation for the "no deal" scenario, although they deny (as they would) that there was anything like a ding-dong.
But one of the cabinet sources suggests Mr Hammond's behaviour is either "deliberate and divisive or politically stupid".
But it led today to what Brexiteers are claiming was a "deliberate slapdown" of the chancellor by Theresa May at Prime Minister's Questions, when she made plain that money would be forthcoming for "no deal" planning as and when it was necessary, striking a rather different tone to the chancellor's "very last moment", comments.
As Numbers 10 and 11 point out, the Treasury has already allocated more than half a billion to specific contingency planning and held back billions in last year's spending round to provide headroom if Brexit goes awry.
But right now, the Treasury is clearly not willing to give in to some of his colleagues' demands to write big cheques for the "what if".
For Mr Hammond's team it makes no sense to be spending money when there's hardly any around, unnecessarily, and certainly not to send political signals to Brussels.
But for those in the Tory party who already resent and disagree with his attitude, it's another reason to have a pop.
For those of us watching on, it's another sign of how the Tories are consumed with fighting each other over Brexit, rather than the opposition.