The shadow chancellor, Ed Balls, brushed aside George Osborne’s eye-catching tax cuts and got straight to the heart of the problems facing his rival – stagnant wages, worrying borrowing and disappointing revenue receipts.

The senior Labour MP was dealt a customary curveball by Osborne, who omitted to mention his radical stamp duty shake-up until the very end of his autumn statement speech.

But Balls immediately dismissed these “diversionary tactics” and “pre-heated re-announcements”, then fired off a series of questions about why the chancellor was not facing up to the concerning outlook.

“The Office for Budget Responsibility confirms that stagnant wages and low-paid employment have hit revenues,” he said. “Can he tell us this year how much tax revenue has been lost because of stagnating wages and forced part-time employment?

“The result of this shortfall in tax revenues is that – once again – I believe the chancellor has had to revise up his forecasts for government borrowing … So in his answer can he tell the House, how much has borrowing this year been revised up compared to his budget target?”

After tackling him on the deficit, Balls noted growth had been revised downwards “year after year after year” from 2016 onwards.

Osborne thought he had got his rival into a corner by calling a vote on the stamp-duty changes on Monday, as it would force Labour to decide whether it supported this or favoured a mansion tax on homes worth more than £2m.

However, Balls appeared unruffled as he suggested Labour could be in favour of the stamp duty reforms, which the party will support, as well as annual taxes on high-value property.

Balls also pointed out further omissions in the autumn statement, saying there were “no details at all” about how Osborne would pay for £7bn of unfunded tax cuts promised after the next election. He said this had even been called a “fantasy” by Vince Cable, the Lib Dem business secretary, who looked uncomfortable on his frontbench seat squashed next to two Tory cabinet ministers. “Is the chancellor planning to pay for it with a further rise in VAT?” Balls wondered.

Heavyweights on both sides of the House of Commons then stood up to support their financial spokesmen. Ken Clarke, a former Conservative chancellor, said Balls’s conversion to fiscal discipline seemed somewhat “quaint and ridiculous” given his Treasury role under the last government.

Meanwhile Alistair Darling, a former Labour chancellor, challenged Osborne on how he was going to get enough tax revenues to hit his deficit reduction targets, given the lower growth forecast in the next parliament.

Backbenchers appeared to be in an uproarious mood, after David Cameron earlier botched a sex joke about Balls by nonsensically accusing him of “maso-sadism”. After that failed gag, Osborne raised a few more laughs with his suggestion that Ed Miliband should take a speaking part in Wallace and Gromit to replace a retiring actor, given that he will be a “suitable and available candidate” after the election.

The chancellor then had his party in stitches by using an announcement about British involvement in exploration of Mars to claim he had long gazed at the “barren wastelands of the red planet” and given up on finding intelligent life there.

Aides insist Osborne came up with his own gags, although his speeches tend to be a team effort aided by friends such as Lord Finkelstein and his closest economic adviser, Rupert Harrison.

In contrast, Balls was lighter on the scripted laughs, but thought on his feet as John Bercow, the Speaker, ordered a disruptive minister to pipe down or get out. The shadow chancellor cheered his troops by roaring: “Don’t worry, we’ll get him out next year.”