The Scotsman was sacked in April, less than 10 months after taking charge at the club following Sir Alex Ferguson's retirement.
During his stint as boss, the Red Devils dropped from champions to seventh last season, which caused the club to recruit new manager Louis van Gaal.
According to the Daily Star, the North-West outfit lost £35m in prize money after failing to qualify for the Champions League under Moyes, who cost the club around £7m in wages despite not completing a full season in charge.
Reports have claimed that United also lost out on around £8.5m in prize money for finishing in seventh spot under Moyes in the Premier League.
Today, United are expected to reveal their accounts for the year ending June 30, 2014, which is predicted to show revenue of between £420m and £430m.