I am the person behind the second most-debated figure of the Labour leadership race – the £93bn corporate welfare bill. I write “debated”, but this is too generous to some of those who have passed judgment on the work.

Once Jeremy Corbyn had begun campaigning on the basis that some of the £93bn could be saved, proper analysis and discussion gave way to myth making and conjecture, and I didn’t recognise many of the arguments that were attributed to me.

Despite being mentioned at some point by just about all of the media outlets, the only journalist who contacted me before writing about my research was Aditya Chakrabortty, who wrote the original front-page splash for the Guardian based on my report. I’m hardly surprised then, if disappointed, that publications as venerable as the Economist have got basic things confused in their rush to write off Corbyn and my research.

The £93bn handshake: businesses pocket huge subsidies and tax breaks Read more

The report was published in July by the Sheffield Political Economy Research Institute and builds on years of researching and writing about public and social policies. Each category of corporate welfare I identify – made up of the various forms of state provision that service the needs of businesses – builds on the work of British and international academics, journalists, governmental organisations, politicians, policymakers and think tanks.

Businesses could not do business without huge amounts of government support. They require legal protections, a state-backed currency, the right frameworks to hire and fire and essential infrastructure. They depend on financial backing to exploit innovations and invest.

And public policies operate to socialise various corporate risks. Employers need educated and healthy workers. Unemployment benefits and pensions increase labour market flexibility, making it easier to hire, fire and retire employees. The annual Global Competitiveness Report clearly illustrates the importance of comprehensive state provision to economic growth, productivity, profitability and national competitiveness. And it is published by the World Economic Forum – the organisation that runs the Davos gathering, so hardly a mouthpiece of the left.

The £93bn estimate, in fact, excludes most of the above. It is made up only of more direct benefits and services. It doesn’t include the indirect benefits that accrue to businesses from the social welfare system and the legacy costs linked to the bank bailouts. It doesn’t even include the cost of in-work tax credits, which have been labelled corporate welfare by others, including Conservative MPs.

The more direct categories of corporate welfare identified in my report include official estimates of the cost of subsidies and grants to companies, worth about £15bn a year. Beyond this, the report identifies tax benefits as a major component of corporate welfare, at £44bn. Not surprisingly, this has proved to be the most controversial category of all.

I’m disappointed that some publications got basic things confused in their rush to write off Corbyn and my research

Critics have argued that the largest tax benefits simply recognise that businesses incur costs whenever they invest. But tax breaks – or tax expenditures to give them their correct name – are not provided “as of right”. They are politically determined. They vary widely between states over time, and are provided with specific objectives.

My data comes from the HMRC’s annual Tax Expenditures database. Tax expenditures, including capital allowances, were identified as a key business subsidy in a report by the Office for Fair Trading in 2004. The National Audit Office has defined tax expenditures as being “reliefs with similar aims to spending programmes”, and explains that tax expenditures, including capital allowances – offer “a low-cost way of providing financial support to businesses”. This is not to argue that all tax breaks for businesses are unjustified. But they do form part of the corporate welfare state.

Another issue that has proved to be controversial is my inclusion of procurement as a form of corporate welfare. In fact the Department of Trade and Industry included procurement in its analysis of subsidies back in 2004, and the WTO’s agreement on Subsidies and Countervailing Measures (SCM) argues that procurement is a potential subsidy since purchases are made “under circumstances that do not accurately reflect normal market conditions”.

The size of the UK procurement budget is huge, and it is growing as more and more is transferred from the public to the private sector. My estimate of the size of the procurement budget is based on an attempt to get at the “above-market” charges levied on procured goods – which on the basis of two different methods, is set at around 6.5% of the total procurement budget. This results in an estimate of about £15bn.

The unemployed have ‘no rights without responsibilities’, whereas corporations have no such strings attached

I do not argue in the report that it is either possible or desirable to cut £93bn from the corporate welfare budget. What I have called for is an acknowledgement of the basic principles and a full and informed debate. I am grateful to the new Labour leader and the shadow chancellor for pushing corporate welfare further up the political agenda. I would urge them now to engage more fully with the issues involved, rather than see corporate welfare as an easy budget item to cut.

They could investigate whether the millions paid out to individual companies in grants and subsidies in recent years bring sufficiently wide public benefits. They could ask the government why it continually emphasises the duties of social welfare claimants while turning a blind eye to the behaviour of corporate welfare claimants.

They might inquire why unemployed citizens on benefits are continually told they have “no rights without responsibilities”, whereas corporations are provided with financial support without such strings attached. They could also ask why the public disclosure of subsidies and grants paid to private businesses doesn’t even come close to fulfilling the government’s own transparency agenda. They should challenge business organisations such as the CBI to say which aspects of corporate welfare should be cut in order to pay for ever-greater tax cuts for businesses.

Most important of all, they should use their influence to press for a full audit of corporate welfare. And in so doing, they may find that this is an issue that they could build a consensus on.

• A longer, fully referenced version of this article is available here