However, chairman Douglas Park and director John Bennett have agreed to continue providing the Ibrox club with loans to cover the shortfalls.
The cashflow issue was acknowledged in the Light Blues' latest annual accounts, which show Rangers made an operating loss of £15.9m for the financial year up to June.
That figure is a £4.3m increase on last year's losses and comes after the 2019-20 season had to curtailed early in March because of the pandemic.
Rangers did, however, see revenue increase by around £6millions thanks to increased UEFA prize money on the back of the club's run to the last 16 of the Europa League last term and a new kit deal with Castore, while they again sold out their season-ticket allocation to fans who have been forced to watch their team in action via the club's online TV channel.
And with supporters still barred from entering stadiums across the country due to Covid-19, Rangers chiefs acknowledge there remains uncertainty over the club's financial picture as they face up to months still without vital matchday revenue streams.
In its 'going concern' section, the report notes: "At the time of preparation, the forecast identified that the Group would require £8.8m by way of debt or equity funding by the end of season 2020/21 in order to meet its liabilities as they fall due with further funding of £14.4m required by the end of season 2021/22.
"The first tranche of funding is required from investors before the end of November 2020. However, the final amount required is dependent on future football performance, European football participation, player trading and the ongoing impact of Covid-19 amongst other factors."
It adds that Park and Bennett have reached an agreement with the Ibrox board that they will see them "provide additional loan facilities as necessary to meet shortfalls".
Park - who stepped up to replace Dave King as chairman earlier this year - has already succeeded in winning fresh investment in recent weeks, with Japan-based businessman Stuart Gibson ploughing £8million into the club last month.
And the chairman said in his statement to shareholders: "When I returned to Ibrox in March 2015, I advised my fellow shareholders and directors that I believed it could take us a decade to restore our beloved club to where it belonged, both on and off the field.
"I think we are in a somewhat better position today than I had envisaged but there is much work to do.
"The financial year under review is unlike any other, no matter the business or walk of life. The impact of Covid-19 will have far reaching consequences for our economy and society. Rangers is not immune to the severe effects of this unprecedented challenge.
"This is a club which has experienced some of the darkest days that any football club can endure. This is a club which has repeatedly displayed remarkable resilience in the face of adversity and which will do so yet again.
"This resilience, together with a burning ambition, has, once again, been underpinned by significant investment from our directors and shareholders. Our club continues to attract investment from across the world, and I believe this will grow further as our resurgence builds momentum.
"Covid-19 has brought with it the severest of strains to all of our business and personal lives. As we can see from the plight of a number of clubs throughout Europe, football is facing some very serious challenges.
"Indeed, playing matches behind closed doors is likely to adversely impact the club by in excess of £10m in the current season.
"Yet I am confident in your board and our employees to face these challenges with the backing of our magnificent loyal supporters."