More than £2 billion has been spent in response to the coronavirus pandemic in Northern Ireland, the audit office said.
Three ministerial directions ordering speedy payment of support grants to businesses were issued by economy minister Diane Dodds.
There have been ministerial directions across other UK jurisdictions on Covid-19 initiatives.
The Department for the Economy offered support to local businesses struggling to survive as a result of public compliance with social distancing and isolation regulations, the watchdog said.
Due to the tight timeframe Ms Dodds’ officials had concerns as to whether they could provide sufficient evidence of the likely value for money of the schemes, or sufficient assurance on the risk of loss through error or fraud, a report said.
By July 24, the UK Government had confirmed that it would provide £2.2 billion to Northern Ireland to fund Covid-19 initiatives.
Comptroller and auditor general Kieran Donnelly said: “The challenge of responding to the Covid-19 pandemic is unlike any the Northern Ireland executive has ever faced.
“The scale of its response is similarly unprecedented. The executive was required to quickly introduce multiple measures supporting vulnerable individuals and businesses facing a major reduction in income.
“My report gives an overview of these measures, but no assessment of the value for money of individual measures has been made at this point.”
The total cost of the Covid‐19 response relating to Northern Ireland, at August 2020, is estimated to be just over £2 billion, the spending watchdog said.
This excludes the Northern Ireland cost of the furlough scheme.
The approach to measuring regional expenditure is still being refined, and so the cost relating to Northern Ireland cannot be established at this time, the audit office said.
When known, this will increase the total estimated cost materially, as almost 250,000 employments have been furloughed by August.
Grants paid to local firms by the economy department included those worth £25,000 for hospitality, retail and tourism businesses, a £10,000 grant for small companies and a micro-business hardship fund.
Mr Donnelly added: “There will undoubtedly be important lessons to learn, and this report provides my office with the basis for a programme of work evaluating how public money has been spent during this period.
“For example, as an initial step, we intend to examine arrangements surrounding the supply of personal protective equipment in Northern Ireland; the support provided to lessen the impact on vulnerable groups; and the wider impact of Covid-19 on public sector income.”
To this point, the Stormont executive’s response to Covid-19 has been funded by £1.28 billion received from the UK Government or the executive and approximately £465 million either reallocated from within existing Northern Ireland departmental budgets, or part of additional departmental bids submitted to the executive.
Approximately 70% of total estimated costs identified in the report relate to activities across three departments, health, economy and finance.
The Department of Health funded working at the front line, treating infected patients.
The Department of Finance offered a range of business and rate reliefs for individuals and businesses.
A spokesperson for Department for the Economy said: “The department is content that it took the necessary, swift action to support tens of thousands of businesses facing serious difficulties, or failure, caused by the Covid-19 crisis.
“The measures taken by the minister were supported by the executive. The evaluation of these schemes will take place in due course.”