This is despite there being a pledge in the Coalition agreement to change the tax system to support marriage.

The Chancellor has been accused of ‘kow-towing’ to the Liberal Democrats by the refusal to include measures.

However, senior Treasury sources have told the Sunday Telegraph that the idea will not feature in next month’s crucial financial package.

Stewart Jackson MP, who stepped down from the Government last year as a ministerial aide, said deferring the introduction of marriage tax allowances represented a ‘failure of leadership’ by David Cameron.

‘I urge George Osborne to reconsider this decision,’ he told the newspaper. ‘There is a great deal of evidence that shows marriage has many economic and other benefits to society.

Britain is one of few European countries that fails to recognise marriage in the tax system.

‘Not to introduce this feels like kow-towing to the Liberal Democrats. ‘Our supporters say they want this and they put us where we are. We need to deliver what they want.’

However, it became a byword for being given the sack.

A plan to replace the form with a “leaver statement” has now been dropped by HM Revenue and Customs.

New regime

HMRC is moving to a system of Real Time Information, under which staff movements will be recorded much more quickly. Trials start in April.

It had been thought that the P45 – which has been in existence since 1944 – would be unnecessary and its days were numbered, but HMRC said it would be retained.

“Employers told us to keep the P45, which is exactly what we have done,” said Stephen Banyard, head of personal tax.

Under Real Time Information procedure, P45s will be given to the employee to take to their next employer.

The move was welcomed by the Chartered Institute of Taxation (CIOT), which said that removing the P45 would have been confusing.

“P45s are widely recognised and widely used, not just by new employers, but by banks, tax advisers and public bodies, as evidence of identity,” said Colin Ben-Nathan, of the CIOT.

“Introducing an alternative document alongside the P45 without an adequate educational process and amendment of rules and training manuals would be confusing and likely to increase bureaucratic burdens, the opposite of the government’s intentions.”

Chas Roy-Chowdhury, head of taxation at the ACCA, an accountancy body, said that withdrawing the P45 would have meant the end of standardisation of this paperwork.

This would have caused problems for tax calculations, he said.