The bill facing the government for subsidies and tax breaks for businesses hit by the Covid-19 outbreak has already reached more than £100bn, according to the Treasury’s independent economic forecaster.

The Office for Budget Responsibility said Rishi Sunak’s schemes to protect businesses through the worst of the downturn amounted to £103.6bn of taxpayer support.

It said a new database would track the chancellor’s policy interventions, which have already been extended several times in recent weeks following pleas from business groups for further funding.Among the costed measures documented by the OBR are the main grants schemes for businesses, including the furlough scheme that pays up to £2,500 a month for each member of staff sent home.

However, the coronavirus interruption loan scheme (Cbils), which has supported businesses with £4bn of credit, is excluded, while it remains unclear how many firms will default, leaving the exchequer to pick up the bill. A £750m fund for startups is also excluded from the OBR’s costings for the same reason.

The final bill for taking over the UK’s rail franchises, lost tax revenues from VAT, income tax and a dive in property transactions will feature in a broader measure of costs to the exchequer, most likely in the autumn.

Among the costs that are included are:

• £39bn Coronavirus job retention scheme (furloughing).

• £16bn Public services spending for health services, local authorities, measures to support vulnerable individuals, supporting rail services and funding for the devolved administrations.

• £800m Additional funding for charities.

• £500m Local authority funding to support vulnerable people (hardship fund).

• £10bn Self-employed income support scheme.

• £15bn Small business grant schemes.

• £13bn Business rates package.