Former Conservative Chancellor Lord Lawson says he is minded to support the bishops' motion expressing regret about the reforms. George Osborne clearly wants to get most of his savings from the welfare budget, Lord Lawson says, and tax credits are a large part of that budget. But he says "some aspects of this measure will need to be reconsidered and changed".

Talking about the impact the proposed policy would have on carers, lone parents, children, low-paid workers and small business owners, Labour peer Baroness Lister urges her fellow peers to advise the government to think again. She also suggests that the government had not adequately considered the impact of the proposed policy.

Ross Hawkins
Political correspondent

The Prime Minister's spokeswoman has suggested it may be impossible to remove VAT from sanitary products.

Asked about a motion demanding ministers negotiate with the EU to be allowed to apply a zero rate, she said: "What is being proposed is not something that being looked at we think is achievable."

The government sympathised with the issue and understood the concerns, she said. But a zero rate would only be possible with the support of every EU nation, she said.

Pushed on whether that meant the government would not seek change, she said it would be "difficult to achieve".

A rebellion is possible this evening as several Conservative MPs have signed a Labour motion demanding change.

Some are using the debate to highlight the powers of the EU. The prominent Eurosceptic Steve Baker said: "The great thing about this issue is it explains to people in a very simple way what it is to lose sovereignty."

I've been told that a number of Tory MPs may refrain from supporting the motion if ministers offer a commitment to seek a negotiation during the debate.

But the spokeswoman's words suggest the government believes substantial change is unlikely.

She stressed the UK applied the lowest possible rate of VAT on sanitary products under EU rules - 5% compared to an EU average of 17%.

Presenting her own amendment in the House of Lords on the tax credit changes, Labour peer Lady Hollis says it was a delaying motion rather than a fatal one so it wouldn't kill the bill. Under her proposal, "the cuts would apply to new claimants only" and could be "implemented next April exactly as planned".

She denied the motion she was presenting broke any conventions on the Lords not blocking financial bills. 

Image source, bbc

Putting forward his "motion of regret", the Bishop of Portsmouth, the Right Reverend Christopher Foster, says the tax credit cuts are "morally indefensible".

Bishop Foster says his motion offers an "alternative" to those put forward by political parties for the House to register its disapproval.

Image source, The Green Party

Green Party peer Baroness Jenny Jones says she will vote for the Liberal Democrats’ motion to stop the Conservative government’s cuts to tax credits. She said she will also vote, if necessary, for the crossbench and Labour motions which aim to mitigate and stagger their impacts. She said:

The World at One
BBC Radio 4

The government's changes to tax credits would "penalise" those in work, according to Deven Ghelani the director of consultancy Policy in Practice.

He told the BBC earlier that even taking into account the government's mitigation measures - such as the increase in the national living wage - two thirds of households who receive working tax credits will still be worse off, with some losing more than £1,000 a year.

Any government changes designed to balance the books should not be done by penalising those in work, he added.

Presenting her motion to delay the tax credit reforms, crossbencher Baroness Meacher said she is "acutely conscious" of threats by the government to "destroy this House one way or another if we proceed".

Robin Brant
Political Correspondent

The government has signaled it may alter plans to cut tax credits, but only if the House of Lords steps back from blocking the proposal.

Peers are due to vote on a statutory instrument which would implement the changes that would save the government £4bn next year but could see millions of families thousands of pounds in working tax credits.

It's looking increasingly likely that the Lords would block the measures.

The Cabinet Minister and Leader of the Lords Baroness Stowell opened the debate by telling peers that the chancellor would 'listen very carefully' to their concerns about the impact of the changes, but only if the lords didn't block the proposals.

Lib Dem work and pensions spokeswoman Baroness Manzoor is putting forward her "fatal" amendment. The impact of the cuts on tax credit claimants will be "devastating" she says.

If the Lords votes for one of the motions to delay or cancel the tax credit changes, Baroness Stowell says:

Lords leader Baroness Stowell tells peers Chancellor George Osborne would "listen very carefully" if a motion of regret put forward by Church of England bishops was passed by the House of Lords. But this can only happen if the other motions, which would delay the tax credit cuts or scupper them altogether, are rejected.

Image source, Getty Images

One of the foremost constitutional scholars in the UK has said there is "no source" from which the Lords can derive the authority to defy the Commons over the issue of tax credits. Professor Vernon Bogdanor, who was David Cameron's tutor at Oxford, has told the BBC that this a "very serious clash" between the two Houses that can only resolved by enshrining into law the centuries-old convention that the elected chamber has total supremacy over financial matters. 

The House of Lords is pretty much full for the high-profile debate on tax credits which is now getting under way. 

It is not only Rachel Treweek, Bishop of Gloucester, who has been sworn into the Lords today. Andrew Lansley, the former health secretary and leader of the House of Commons, has also joined the Upper House.   

House of Lords
Parliament

Peers have greeted the introduction of the first woman bishop in the House of Lords with a very rare round of applause. As a new peer or bishop takes their seat for the first time, it is customary for the House to murmur its approval. As with MPs in the Commons, it is not the custom for peers to applaud.

Two women bishops have already been appointed but Rachel Treweek, Bishop of Gloucester, is the first woman to run a diocese and to sit in the House of Lords.