More from Capital Economics on the key measures to look out for in the Budget.

Measures that have already been announced and are due to come into effect in 2017 include a national productivity investment fund which will cost the Treasury £2.4bn.

Increasing the personal allowance to £11,500 and the higher rate threshold to £45,000 will cost £2bn.

Permanently doubling small business rate relief will cost £1.6bn.

The fuel duty freeze from April will cost £800m, and cutting the corporation tax from 20% to 19% will cost £600m.

But, on the yield side, other corporation tax changes will bring £1.3bn into the Treasury, while a 2 percentage point increase in insurance premium tax will bring in £700m.

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Yesterday Capital Economics sent out its checklist to help people keep track of key Budget announcements, which is very handy and well worth a quick recap.

Possible new Budget measures include raising the higher income tax rate threshold to £47,500, which would cost the Treasury £1.9bn, and raising the personal allowance by a further £250 to £11,750, at a cost of £1.4bn.

Extending small business rate relief could cost £1bn, while an air passenger duty cut would cost £400m.

Social care emergency funding could cost £1bn, and additional  schools spending £500m.

On the receipts side, increasing National Insurance contributions from the self-employed could yield £1bn, and a rise in alcohol duty could bring in £100m. Unspecified tax avoidance measures could yield £1bn.

Today Programme
BBC Radio 4

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As is traditional, the BBC is out taking the temperature of the UK economy on Budget day.

Peter Smyth is a director of the Swansway Group, which runs a string of car dealerships, including Crewe Volkswagen. He admits that last year, before the Brexit vote, they were nervous, but says so far nothing has changed.

In fact, not only are people still buying cars, but he's been selling more than last year, and more than before the referendum, he says.

In part that's because it's cheaper than ever to buy a new car thanks to cheap finance - and there's been an increase in people borrowing to lease cars.

But isn't that just shopping on the never-never, asks Today's Nick Robinson?

"We're just in a world of the never-never," says Mr Smyth. "Is your mobile phone any different?

The FTSE 100 is trading slightly down in early trading ahead of today's Budget announcement, down around 0.06% at 7,334 points.

The biggest fallers are miners Randgold Resources and Fresnillo.

Paddy Power Betfair shares are bouncing back from yesterday - the firm tops the risers.

Today Programme
BBC Radio 4

Simon Jack, the BBC's Business Editor gets the final word in the Today Programme's prediction-pooling exercise.

He thinks the Chancellor will be sending out positive signals to business: 

"He needs business to invest. He'll be sending the message: if you want to spend money, if you want to take on people, we're at your back."

Douglas Fraser
Scotland business & economy editor

Today Programme
BBC Radio 4

This budget will not feel like the "some-might-say nakedly political budgets of George Osborne" says the BBC's Political Editor Laura Kuenssberg. But it will still be political, because every budget is political. 

For example the money for new free schools that could be de facto grammar schools - that's a favoured project of the Prime Minister. And she suggests there could be signals of more radical changes for the longer term especially in areas such as social care, changes to the tax system, and the role of technology in the economy. 

But don't expect too much she says. People close to Philip Hammond say we should see this as the warm-up act for his main Budget in the autumn.  

Today Programme
BBC Radio 4

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More thoughts from the BBC's Economics Editor Kamal Ahmed on the Today Programme... 

Apart from our relationship with Europe which inevitably dominates, Kamal says the other big strategic issue in the chancellor's in-tray is what to do about the "gig" economy - that's Uber and Deliveroo and the like. 

The trouble is he doesn't get enough tax from these workers, categorised as self-employed, or their employers. Kamal predicts we'll see more in today's Budget about how to equalise the tax take from the permanently employed with those in the "gig economy".

Today Programme
BBC Radio 4

The BBC's business editor Simon Jack, economics editor Kamal Ahmed, and political editor Laura Kuenssberg are gathered around their collective crystal ball.

Kamal said the Treasury likes to see itself like the Eyeore while the rest of the cabinet are over-excitable Tigger characters when it comes to spending. 

There are risks on the horizon - Kamal points to Brexit risks, Trump risks, inflation, and government borrowing costs as a looming risk.

Laura says that in the short term it's the "creaking and groaning" social care system that may get some spending. But she says we should also expect a review of the longer term provision for social care. 

And she's in agreement on Kamal's characterisation of the Chancellor. She says he's "a Chancellor who genuinely likes spreadsheets". There will be "nothing flash" in this Budget.

Simon Jack says businesses will be hankering after a comforting tone from Mr Hammond. People will be looking to see if there's any new money to ease the pain of the business rate rises. 

Rory Cellan-Jones
Technology correspondent

Kamal Ahmed
Economics editor

The FT has Chancellor Philip Hammond lining up a Brexit Budget on its front page. While the Treasury will be buoyed by better-than-expected growth and tax receipts, the Chancellor will build up his £27bn Brexit "insurance fund", it says.

The Telegraph says Mr Hammond is likely to announce higher taxes on the self-employed, while the Guardian says he could face pressure to put more money into public services.

As the UK heads towards Brexit, government finances look in unexpectedly good shape. But does that give the chancellor room for tax cuts or spending increases?

The BBC's business editor Simon Jack, economics editor Kamal Ahmed, and political editor Laura Kuenssberg give their views.

Today Programme
BBC Radio 4

Jane Sydenham Investment Director at Rathbones reckons the chancellor will be treading cautiously today: 

"We've got a period of uncertainty coming up over the Brexit vote and he's going to have to be quite careful."

"We've also got the fact that inflation is picking up and although economic growth figures are quite good at the moment that may start to have an impact on the consumer."

"The inflation number is probably going to move up to two-and-a-half maybe even three percent and that does start to eat into spending power."

Today Programme
BBC Radio 4

Radio 4's Today Programme as you'd expect is out and about for budget day. 

This time they're in Crewe at AO - the online retailer that sells a lot of household appliances like microwaves and washing machines - watching the fork lift trucks get the morning shift off the ground.

Dave Ashwell, logistics director at the company, says although the company employs a lot of non-UK workers and trades in a lot of imported stock, they're pretty optimistic.

"I think there may be some anxiety in the country but the internet is a growing business so we're still confident that whatever happens in the country we'll continue to grow."

Today Programme
BBC Radio 4

Shaun Cafferty from Crewe's local chamber of commerce suggests the chancellor might want to spend a bit more time listening to small and medium-sized companies - rather than the big guns who he reckons tend to have better access to the politicians' ears. 

Though he's not expecting too much.

"We've got to recognise we can't be too idealistic as the Chancellor has limited room for manoeuvre."

But what would he like to see?

"We'd like evidence that the new Chancellor has a better feel for small and medium sized business."

"They've spoken a lot about consumers and families who are just about managing. I think they've got to realise there are a lot of small and medium sized businesses who are also 'jams'."

He says the combination of the new national living wage, pension auto-enrollment and now the changes to business rates are making life tougher for smaller businesses.

He says a third of the workforce works for a company employing 50 people or fewer. So what the chancellor does affecting smaller companies could have a big impact, he says.