Hayes & Yeading have lost their appeal against relegation from Conference South.
The FA announced on Friday afternoon that it had upheld the initial decision by its own league committee and United should plan for life in the Southern Premier.
United’s appeal centred around Vauxhall Motors, who tendered their resignation from the Conference North last March, thus freeing up an extra space at step two for next season.
Oxford City are the ones who benefit, remaining in the division despite finishing third-from-bottom on 37 points.
But Hayes & Yeading, who also play at step two and finished third-from-bottom in the Conference South, say that they should be the ones spared.
United ended the campaign on 45 points, eight more than City, and the club reckoned that superior points total should see them safe.
Rule 5.4 (i) of the regulations for the operation of the National League System, published by the FA, states: “Where a vacancy occurs in a particular division prior to the end of a playing season, the club creating the vacancy is taken to be the club in the bottom position in that division.”
In a statement United said: Hayes & Yeading are disappointed to announce that an appeal hearing of the Football Association has today upheld an initial decision by its own League Committee.
"Accordingly, Hayes & Yeading have been advised by the authorities to prepare to commence season 2014/15 in the Southern League Premier Division.
"Despite accusations to the contrary, the club has expedited all routes of appeal as quickly as the system has allowed.
"The club reserves its right to take this matter further in pursuit of the correct application of the rules and will not be making any further comment at present."
