A N EPISODE OF “The Simpsons” ends with a tragicomic moment. Homer Simpson has bungled his new role as Springfield’s sanitation commissioner, leaving rubbish piled high in the streets and spewing from drains. A native American, unaware of the litter-strewn city behind him, picks up a discarded packet of crisps and sheds a tear at man’s disrespect for nature. “Do yourself a favour,” counsels his friend. “Don’t turn around.” Philip Hammond is in a similar position as he prepares for the budget on October 29th. The chancellor’s immediate problems look bad enough, but they are nothing compared with the mess looming behind him.

The defining domestic policy of British governments since 2010 has been cleaning up the public finances. In that year the budget deficit (spending minus tax) was 10% of GDP , the biggest since 1945. Eight years of austerity later, it is down to 2%. Mr Hammond hopes to keep it below that level. If he succeeds, and nominal GDP grows by at least 2% a year, the ratio of public debt to GDP , currently 85%, should fall.

In his quest to reduce the debt pile, Mr Hammond has recently received some good news. The latest figures put annual nominal GDP growth at nearly 4%, above expectations. Between April and August the government borrowed £18bn ($24bn, around 1% of GDP), putting it on track to borrow £10bn less over the fiscal year than was expected by the Office for Budget Responsibility ( OBR ), the fiscal watchdog, when it made its forecasts in March.

Yet in other ways, his task has become trickier. Theresa May announced earlier this month that “the end is in sight” for austerity. She has promised that the health service will get a £20bn boost and that fuel duty will be frozen for the ninth year running. Tory MP s, meanwhile, are calling for universal credit, a big welfare reform, to be made more generous. All this extra spending imperils Mr Hammond’s plans.

There is little scope for trimming departmental budgets, most of which have already been cut to the bone. So the chancellor is considering tax rises. But here he is constrained by last year’s Conservative manifesto. Mr Hammond has already hinted that he might break a promise to increase the tax-free allowance from £11,850 to £12,500. (The need to fund extra health spending, he explains, was “something that we didn’t anticipate at the time we wrote our manifesto.”) Freezing that threshold until the end of the parliament might raise £5bn a year, but would kick up an almighty fuss within the Tory party. The manifesto also promised not to raise VAT . But applying the tax more broadly might not quite amount to breaking a promise. It would also be economically wise. VAT is an efficient tax but Britain’s system is leaky, with myriad exemptions. The government could start charging it on food (raising up to £20bn). That would hit the poor, but a more generous universal credit could offset the damage. Other options may be politically easier. Cancelling a planned cut in corporation tax from 19% to 17%, to raise £5bn, would break another manifesto commitment but might not face as much parliamentary opposition. Rumours swirl that Mr Hammond wants to restrict income-tax relief on pension contributions to the basic rate of 20%, rather than the saver’s marginal rate. Doing so could yield £10bn a year. Mr Hammond would be pleased just to get himself out of the latest fiscal hole. But like Homer Simpson’s piles of rubbish, bigger problems are mounting. The first is Brexit. Though the OBR has taken some account of the damage that leaving the European Union will cause, it seems to be banking on a soft exit. It assumes that trade will continue without much disruption and that immigration will remain fairly high. Yet Britain is on course to leave the single market and end free movement, and the possibility of a “no deal” exit is growing.