It’s sometimes surprising what you can find on gov.uk, the official government website. There’s an article there called Prime Ministers and their Chancellors. It starts: “The connection between the prime minister and chancellor of the exchequer is probably the most important, and potentially the most problematic of all ministerial relationships. Foreign secretaries and home secretaries . . . rarely have the capacity that a chancellor does to define, or indeed destabilise, a premiership.”

The tensions between Lawson and Thatcher, Brown and Blair, Hammond and May did, indeed, help to both define and destabilise those premierships. At times, as with Brown and Blair, the tensions centre on ambition and desire to stamp authority across the government. The more fundamental tensions, though, are often those between economic and political management. Channelling Treasury analysis, Philip Hammond made the case for the closest possible trading relationship between the UK and the EU. That’s where the economics pointed. The politics pointed elsewhere.

The recent tensions between Nos 10 and 11 would appear to exemplify a more traditional source of friction: the Treasury desire to keep the public finances under control butting up against prime ministerial ambitions to spend money. It looks like Sajid Javid, our now ex-chancellor, won the first round in that battle by getting the commitment, set out explicitly in the Conservative manifesto, to target the present budget balance — in other words, to borrow only to invest. Given that the current budget is only just in surplus, that is a serious constraint. It leaves the government essentially no room to increase day-to-day spending unless accompanied by tax rises.

For a government that came to office at least implying, if not promising, that the spending taps would start to open and that taxes would not rise, this poses quite the dilemma. There is plenty of room within the fiscal framework, as set out in the manifesto, to invest in infrastructure, to build new stuff. Absent tax rises, there is next to no room to reverse cuts in spending on local government, universal credit, prisons, social care, the justice system or any of the other public services that have borne the brunt of a decade of austerity. That no doubt explains recent stories suggesting that Mr Javid was considering raising taxes on capital gains, expensive houses and pension contributions.

So where is Rishi Sunak, the new chancellor, to turn as he prepares his first budget, which may or may not take place on the advertised date of March 11? His choices don’t look appealing. He could announce an overall spending envelope going forward that, far from marking a decisive break with austerity, offers little or nothing to those hard-pressed public services. If he wants to be more generous, as it would seem his new neighbour at No 10 would like, then he has two options: he could find some serious tax rises; or he could junk the fiscal promises placed before the electorate in December.

Economically speaking, tax rises are perfectly feasible. We are not a highly taxed country by western European standards. Some of the ideas apparently coming out of the Treasury make a lot of sense. The under-taxation of capital gains, especially through the grossly misnamed entrepreneurs’ relief, is little short of scandalous. The same could be said of the way that council tax impinges far more heavily on those living in modest homes in the north than on the inhabitants of mansions in Kensington and Chelsea. For serious money, he probably would have to look elsewhere. There’s a lot of money in pension tax relief, which likely is one reason that kite has also been flown. Unfortunately for Mr Sunak, his predecessors have already raided the pensions of seriously high earners. To get much more, he would need to start hitting those on somewhat more modest incomes: those, for example, on between £50,000 and £80,000 whose income tax bills Mr Johnson pledged to reduce when standing to be leader of the Conservative party.

In the longer run, tax rises feel all but inevitable. The costs of delivering health, pensions and social care are only going to rise and the pressures on other areas of public spending are not going away. Rather than grabbing at whatever increases look most immediately saleable, maybe Mr Sunak would be better advised to set in train a proper, transparent review of how we should be setting tax strategy for the future, with a remit to identify economically efficient and equitable changes that might also raise some cash. That would be a first for the UK Treasury. Such an exercise is decades overdue.

However, nobody likes tax rises or spending cuts. So what about simply loosening the fiscal straitjacket in which he finds himself? Perhaps it’s a little soon to be reneging on a central commitment in the manifesto. On the other hand, usual political rules don’t seem to apply. And, with interest rates apparently stuck at record low levels, perhaps we can afford to loosen up a little. The trouble with that line of argument, as Rupert Harrison, George Osborne’s former chief adviser, pointed out last week, is that even the present fiscal rules don’t guarantee a falling debt burden. Any loosening would imply accepting a rising debt burden in “normal times”. That can’t go on forever.

Mr Sunak could adopt the Augustinian solution and proclaim that he will be virtuous, but not yet. Borrow more now, but promise, honest, to cut borrowing later. Why anyone should believe that is another matter.

One thing is for sure: the official Treasury will be advising against any loosening of the fiscal stance. The boring, boring realities still apply. If we want more spending, we’ll have to pay for it. That, eventually, must mean more taxes.

This article originally appeared in The Times and is used here with kind permission.