The Rugby Football Union chief-executive Bill Sweeney is expecting a loss between £45-£50m following the pandemic coronavirus.
The spread of COVID-19 has caused over 20,000 causalities worldwide and has already forced the England board to cancel the remainder of all the domestic competition except the Premiership in the 2019/20 season.
Sweeney, who confirmed that the RFU executive members will be taking a 25 per cent salary cut and also announced a £7m relief package for community clubs affected by the coronavirus outbreak.
"The RFU had budgeted for a loss-making year within a four-year cycle due to the costs of the 2019 RWC campaign and hosting only two home Six Nations games," Sweeney said.
"The loss will now be considerably more as we face challenges similar to businesses across the country.
"The RFU's biggest asset is also a major cost and the closure of Twickenham Stadium has a significant impact on the revenues we can generate to re-invest back into the game. In that sense we are like every other club in the Union, when we do not stage matches and events we do not generate revenue.
"Based on our planning assumption we estimate RFU revenue losses over the next 18 months to be approximately £45-£50m and have a firm plan in place to mitigate this."
The RFU chief executive also added that the board has been working with a prediction that the game will resume in autumn and said they will tweak their plans on the basis of how the situation progresses.
"Significant progress has been made on the process for considering the implications of ending the season early," Sweeney added.
"We will ensure a fair and balanced outcome for the game and are now committed to update on this by the middle of April.
"No one can predict every possible outcome of the COVID-19 outbreak particularly with regard to the duration of this crisis and we are managing in the unknown.
"We have modelled three potential scenarios and are working on an assumption based on a medium-term impact with a view to a return to rugby in the autumn.
"We will continue to monitor against this assumption and review and revise planning where necessary."