An exchequer deficit of €6.1 billion was recorded in May.
By contrast, a deficit of only €63 million was recorded during the same period last year.
The latest figures show tax revenues are up 1.3% on May last year, due to an unexpected increase in the amount of corporation tax collected.
However, spending is up 19% on what was planned.
This has been put down to health and income supports such as the €350 weekly Pandemic Unemployment Payment.
Finance Minister Paschal Donohoe says while the signs are positive, it's too early to say how the economy is coping with Covid-19:
"Before we can form a wider view we will need to see the June figures. In particular, we'll need to see how the number of citizens on the PUP and how income performs as we go ahead with the reopening of our economy."
The Minister has also warned that the positive corporation tax take will not last forever:
"Today’s figures show that the expected steep decline in consumption taxes has been offset by a rise in corporation taxes and relatively resilient income taxes. In relation to corporation tax, as I have said many times before, receipts of this order will not last forever."
*Reporting by Shane Beatty