var outstandingBalance = 123;
context.Contracts
    .WhereIsPaid(outstandingBalance)
    .ToListAsync();

public static IQueryable<Contract> WhereIsPaid(this IQueryable<Contract> query, int amount)  
{  
    return query.Where(contract => contract.PaymentAttempts.Any(y =>  
        (y as BankPaymentAttempt)!.AmountPaid >= amount ||  
        (y as VipUserPaymentAttempt)!.IsSuperVip)
    );  
}

var outstandingBalance = 123;
context.Contracts
    .WhereIsPaid(outstandingBalance)
    .ToListAsync();

public static IQueryable<Contract> WhereIsPaid(this IQueryable<Contract> query, int amount)  
{  
    return query.Where(contract => contract.PaymentAttempts.Any(y =>  
        (y as BankPaymentAttempt)!.AmountPaid >= amount ||  
        (y as VipUserPaymentAttempt)!.IsSuperVip)
    );  
}

SELECT * FROM [Contracts]
LEFT JOIN (
    SELECT [pa].[Id], [pa].[ContractId], [e].Property, [e0].OtherProperty CASE
        WHEN [e].[Id] IS NOT NULL THEN N'VipUserPaymentAttempt'
        WHEN [e0].[Id] IS NOT NULL THEN N'BankPaymentAttempt'
    END AS [Discriminator]
    FROM [PaymentAttempt] AS [pa]
    LEFT JOIN [BankPaymentAttempt] AS [e] ON [pa].[Id] = [e].[Id]
    LEFT JOIN [VipUserPaymentAttempt] AS [e0] ON [pa].[Id] = [e0].[Id]
) AS [s] ON [c].[Id] = [s].[ContractId]
WHERE ([e] IS NULL OR [e].Amount > @__input_amount) -- or something

SELECT * FROM [Contracts]
LEFT JOIN (
    SELECT [pa].[Id], [pa].[ContractId], [e].Property, [e0].OtherProperty CASE
        WHEN [e].[Id] IS NOT NULL THEN N'VipUserPaymentAttempt'
        WHEN [e0].[Id] IS NOT NULL THEN N'BankPaymentAttempt'
    END AS [Discriminator]
    FROM [PaymentAttempt] AS [pa]
    LEFT JOIN [BankPaymentAttempt] AS [e] ON [pa].[Id] = [e].[Id]
    LEFT JOIN [VipUserPaymentAttempt] AS [e0] ON [pa].[Id] = [e0].[Id]
) AS [s] ON [c].[Id] = [s].[ContractId]
WHERE ([e] IS NULL OR [e].Amount > @__input_amount) -- or something

class BankPaymentAttempt : PaymentAttempt
{
    public Expression<Func<int, bool>> HasPaid = (int amount) => AmountPaid >= amount;
}

class BankPaymentAttempt : PaymentAttempt
{
    public Expression<Func<int, bool>> HasPaid = (int amount) => AmountPaid >= amount;
}