The charity’s consolidated accounts for the year ending March 2012 show the organisation spent £38,008,000 against an income in the same period of £35,817,000.
The 2012 accounts note the reduction of £1.264m in Arts Council England core grant income over the previous year and "lower than anticipated box office revenues in a challenging economic environment".
The charity’s overall deficit in 2011 was £55,000.
ENO staged 115 performances during 2011/12 and attracted a total audience of 188,000 at 71 per cent capacity. In the previous year, ending March 2011, it had a total attendance of 214,000 at 80 per cent capacity.
A spokeswoman for ENO said: "The results, which will be covered by the company’s reserves, reflect the cut in ACE funding in 2012 and the impact of a very difficult economic environment on ticket sales, in a period of award-winning work, increased fundraising and strong international partnership contribution.
"We are continuing to work creatively with international collaborators and fundraising. In this challenging financial environment, we are also looking at the balance of work that we offer to our audiences and the ticket prices we charge."