Average gates are down 20 per cent from last season and have come at a time when the club have spent more than expected on the playing budget and paying off debts.
Ian Lenagan estimates £865,000 was invested by his family between July and December last year to keep the club ticking over.
The U’s chairman is keen to stress that while the situation is worse than expected, there is no reason to panic.
He said: “Financially, it’s not been the best of years, I have to say.
“We’ll lose probably £450,000 this year in terms of profit and the rest of the investment is either in forward investment or stuff we’ve paid off from the past.
“That just means our stake in the club is higher in terms of investment.
“It’s not out of control, it wasn’t out of control when I took over.”
“Every time £100,000 or £200,000 worth of gate receipts don’t come in, then either the club goes bankrupt or we put the money in.
“We’re into Oxford United for the medium and long term and this is a difficult year, because we’ve got losses that we weren’t expecting, in addition to losses we were expecting.”
Just under half of the extra investment has gone to cover non-recurring costs such as paying debts.
The playing budget is £200,000 higher than anticipated, due to the number of loans required to cover injured players, while £100,000 has gone on backroom staff and other investment.
The rest is down to shortfalls in revenue on gate receipts, with average crowds falling from 7,615 in the last campaign to 5,977 this season.
Lenagan urged supporters to come out in force for the remainder of the season.
He said: “I’ve proven I’ll put my money into it and the Lenagan family money into it.
“Any money that comes in from season tickets and increased attendances goes towards the development of the club.
“We’re not making a profit, so it can’t come out to me, it’s going into the club.
“I would appeal that people come in their thousands because the quality of the football we’re playing, the effort the team is putting in on the pitch, is very strong indeed.
“We can be proud of Oxford United again because of where we’ve clawed our way back to. I’d just like people to help a bit and shout a bit more.”