Week ahead

George Osborne poses for the media with the traditional red dispatch box outside his official residence before revealing the 2015 Budget to the Commons

George Osborne's latest Budget will dominate the coming Commons week - indeed, fortnight - as MPs hear the Budget statement and then plunge into four days debate on its content.

The debates will be themed - but we don't know how, because that might provide a clue as to the content of the Budget.

The ritual of Budgets also provides Jeremy Corbyn with his sternest test yet, as Leader of the Opposition; responding to a budget, moments after it has been delivered is a fiendishly difficult assignment, requiring him to keep talking as a research team analyses the information the Chancellor has just provided and feeds him morsels of information and comment which have to be incorporated into the speech as they arrive.

At the same time, the Chancellor will face unusual scrutiny from his own side, as Leave campaigners in the EU Referendum search for subliminal (or overt) pro-Remain messages. He may even be accused, from his own side, of dispensing sweeteners and avoiding unpleasant medicine, to avoid losing referendum votes. It's hard to see how the Budget message can avoid being submerged by Referendum manoeuvring.

Elsewhere, there's plenty of serious legislating going on - notably the Commons debut of the Investigatory Powers Bill, and, in the Lords, the government is braced for a pretty tough week, with a series of defeats on assorted bills and secondary legislation.

First, there's what promises to be a highly tactical battle over the party funding provisions of the Trade Union Bill, where ministers may lose as many as six votes on balloting and political levies. And there may also be more defeats on the Immigration Bill.

Another, slightly longer term, issue to keep an eye on is the slow progress in the detailed scrutiny of the Housing and Planning Bill, where long speeches by a couple of peers have begun to provoke Tory murmurings about an unofficial filibuster.

Already, one extra day has been allocated for these debates, and it might not be the last - and if the bill were not to enter report stage before Easter that would seriously disrupt the legislative timetable. The announcement that the Queen's Speech will be on 18 May sets a deadline for the completion of outstanding parliamentary business - and a long Easter holiday and May day mini-break means there is less time left in the current session of Parliament than a glance at the calendar may suggest....

Monday

The Commons opens at 2.30pm with Work and Pensions questions - and any ministerial statements or urgent questions will be taken from 3.30pm.

The day's main legislating is on the Energy Bill, which delivers Conservative manifesto commitments to support investment in UK energy sources, and produce 30% of electricity from renewable sources by 2020. It sets up the Oil and Gas Authority as an independent regulator and ends new subsidies for onshore wind power.

There are some interesting amendments down for the report stage, with a variety on carbon capture and storage. But watch out for a cross party amendment from among others former Labour Leader (and Energy Secretary) Ed Miliband, the Greens' Caroline Lucas, Plaid Cymru's Hywel Williams, the SDLP's Dr Alasdair McDonnell, the Conservatives Graham Stuart and Daniel Poulter, and Labour's Paul Blomfield.

It requires that the energy secretary shall set a date by which net UK carbon emissions must be zero or lower ("the zero emissions year") by order no later than a year after the Energy Act 2016 comes into force.

In the Lords (2.30pm), the main event is the continuation (into day six of eight) of the committee stage of the Housing and Planning Bill. The issues will include secure tenancies and "pay to stay"; and they may reach the section on planning issues - although progress through these detailed debates has been at a snail's pace, and there is some suggestion that an extra day of committee may have to be scheduled which could push the report stage of this bill back beyond Easter.

During the dinner break there will be a debate marking the Centenary of the Battle of the Somme, led by the Conservative historian, Lord Lexden.

Tuesday

The Commons (11.30am) the day begins with Business, Innovation and Skills questions, followed by a Ten Minute Rule Bill from Labour's Caroline Flint.

She wants to ensure that details of the cross-border tax arrangements of multi-national companies are not only disclosed to HMRC, but also made public. The idea is to highlight where companies are using complicated arrangements to minimise their tax liability. As a member of the powerful Public Accounts Committee, she took part in the hearings with companies like Google - and this bill is one result of that experience. The PAC seems increasingly keen to use this kind of device to highlight the findings of its inquiries.

The main event is the second reading of the Investigatory Powers Bill , which will be the opening move in what looks likely to be an intensive parliamentary battle (see previous blog post). And then MPs debate a de-proscription order on the International Sikh Youth Foundation, under the Terrorism Act 2000 - removing it from the list of banned organisations.

In the Lords (2.30pm), peers continue their detailed report stage scrutiny of the Immigration Bill - where the government lost two votes this week. The key issues include the right to rent, the offence of driving by illegal immigrants, the health surcharge, immigration detention, deport first - appeal later, and the treatments of unaccompanied asylum seeker children- watch out for votes and quite possibly further government defeats on the detention of vulnerable people.

During the dinner break there is a regret motion from Labour Justice Spokesman, Lord Beecham, on the Civil Proceedings, Family Proceedings and Upper Tribunal Fees (Amendment) Order - it might be pushed to a vote. Labour and the Lib Dems are getting quite competitive about opposing statutory instruments put down by the government.

Wednesday

The Commons day opens (11.30am) with International Development questions, followed at noon by Prime Minister's question time. And then comes the Budget - in the subsequent debate watch out for interventions foreshadowing an amendment to the Finance Bill (the measure which puts the Budget into effect) to help women left poorer by state pension age rises - the pension age for women will rise to 65 in November 2018 and 66 by October 2020.

In the Lords (from 3pm) the crucial report stage consideration of the Trade Union Bill begins. The crux of the debate will be the amendment from Crossbencher and former civil servant Lord Burns who chaired a special select committee examining the impact of the bill on party funding.

Labour peers believe proposed opt-in rules for paying into union political funds will devastate the finances of their party. Lord Burns will propose changes that would substantially reduce the impact by applying the opt-in only to new union members. It looks likely there will be a majority for his amendment, so long as the vote is held before the dinner break, when peers often drift away from the Chamber.

As noted above, other defeats may follow - the other issues at play include ballot thresholds, e-balloting, union annual returns, and facility time for union officials, and the government may offer a bit of wriggle room around some technical issues.

But it wants Labour, in particular, to accept the principle of union members opting in to paying money to political parties. If that principle is rejected by the Lords, there are some in Tory high command who would relish the chance to impose the bill via the Parliament Act; if that happens, the bill becomes law in the form in which it left the Commons, which would mean losing the concessions already offered on allowing e-voting for union ballots, for example, which would mean they would be required to introduce a paper based opt-in process for the political levy, within a matter of months.

It's quite a threat and the interesting question is whether Labour and the other critics will be prepared to negotiate a compromise. There's certainly no prospect of the government agreeing a quid pro quo where it promises to introduce restrictions on individual political donations - they argue that Labour introduced curbs on company political funding without any compensating curbs on their own donations.

There may also be a vote on the dinner break business - a regret motion from Lib Dem Baroness Featherstone on the Renewables Obligation Order that ends early the subsidy for small solar installations, which may provide a dessert for the Opposition after the main course in the bill.

Thursday

The Commons opens (9.30am) with a series of mini-question times: three quarters of an hour on Environment, Food and Rural Affairs; and then half an hour for the MPs who speak in the Commons for the Church Commissioners, the Public Accounts Commission and the Speaker's Committee on the Electoral Commission - and that will be followed by the weekly Business Statement from the Leader of the House, and then, the continuation of the Budget debate.

In Westminster Hall, there's a backbench debate on cabin air safety and aerotoxic syndrome led by Jonathan Reynolds, Graham Brady and Dawn Butler. This follows the results of a series of inquests which suggest cabin crew may be at risk

In the Lords (11am), the Housing and Planning Bill committee stage grinds into day seven, with peers due to look at issues around planning and compulsory purchase.

And neither House sits on Friday.