The Hammers' fate was sealed when they squandered a two-goal lead at Wigan Athletic's DW Stadium yesterday, losing 3-2 to fall six points behind at the foot of the Premier League table.
The drop will do plenty of damage to the livelihood of West Ham with one financial expert, David Bick, chairman of Square 1 Consulting, telling Press Association Sport that owners David Gold and David Sullivan will have to brace for a big loss.
"The loss of income from relegation, and this figure factors in the parachute payments, will be between £40-£50million net," Bick said.
"Apart from the loss of media money, there is bound to be a loss in season ticket income, hospitality and other matchday income.
"The Premier League division payment is about £50million while the parachute payment for the first year is £16million, so there's an immediate loss of £34million.
"If they don't secure promotion immediately, West Ham's position will get more severe.
"Given their current position with debts of £80million, it would be impossible to raise finance from bank loans now.
"If the chairmen put in more money as loans rather than shares, that will only worsen the position.
"Sullivan has talked about loans of £20-40million, so the debts could rise to £100-£120million.
"That's a huge number for any club, but especially for a club in the Championship.
"If the owners put that money in, the club's position will be guaranteed for next season.
"If they don't I'd certainly fear for the future of West Ham."