Lancing have been top of the SCFL premier for most of the season and looked well set for promotion under the management of Naim Rouane - who has indicated he will step down if promotion does not happen.
But the FA's decision to write off 19-20 for clubs at step three and below means the Culver Road outfit will have to start again next season in the same division.
A Lancing club statement said: "We have this afternoon been informed by the FA that the 2019/20 season has been concluded and that all results are expunged.
"Lancing Football Club are saddened to hear of the decision taken by the Football Association and National League System to declare that following a premature end to the 2019/20 season, as a result of the continued COVID-19 pandemic, all results have been expunged, with no promotions or relegations to take place between step 3-6.
"There is no doubt that the passion, commitment, determination, patience, diligence and work-rate of our first team manager, Naim Rouane, coaches, players & staff has been second to none this season, evidenced by our sustained top-of-the-table position in the SCFL Premier Division.
"As a Community Club, running 18 teams from U6s to mens, womens and disability, in addition to providing football for the community, huge amounts of time, resources and effort have been put into the first team squad this season, which has been an inspiration & joy to watch across our 18 squads and wider community.
"There is no doubt that the decision to end the season early is a sensible one, to protect the health & wellbeing of all involved, however Lancing Football Club had hoped that, of the decision to void the season or decide positions by Points Per Game (PPG), the latter option would be taken.
"Unfortunately today’s decision has meant that we will remain in the SCFL Premier Division despite our best efforts to earn promotion.
"We are also waiting to hear on what the FA plans to offer in terms of financial support to clubs affected by a premature end to the season, and the registration fees which will approach us over the coming months. We hope that we are given sufficient support to continue operations during these challenging times for us all."
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