Some commentators suggest that tax is going to be one of the important lines dividing the political parties in the 2015 general election. How do political parties formulate the tax policies that make it into their manifestos?

The party in government inevitably has more information through the day-to-day interactions of its ministers with departmental officials, including those at HM Treasury and HM Revenue & Customs. Officials will work on government policy, even if this is not concluded by the election.

Opposition parties are given access to senior civil servants in the six months prior to the general election, on the understanding that their ideas will not be reported back to the ministers. The Second Permanent Secretary at HM Treasury, Sharon White, will supervise access. Members of Parliament are also able to seek information through carefully phrased parliamentary questions.

The government will attempt to pass unfinished business which has sufficient all-party support - because Bills cannot be carried forward to the new Parliament. We expect the Budget to take place as usual in March 2015, with an abbreviated and uncontroversial Finance Bill enacted before parliament is dissolved. Enacting the Bill is essential to continue tax collection, which must be renewed annually.

There will be undoubtedly be a second Finance Bill after the election, including both new and measures not agreed by the opposition for inclusion in the pre-election Finance Act. If there is a change in government, there will also be a second Budget – probably in June.

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