////////////////////////// with LINQ   /////////////////////////
foreach (var item in DC.Loans.Where(a => a.LoanType == 435))
{
   list<Installments> IList = CreateInstallmentTable(item.LoanNumber);
}

public class Installments
{
    public int RowId { get; set; }

    public decimal LoanBalance { get; set; }

    public decimal InterestPerInstallment { get; set; }

    public decimal PrincipalPerInstallment { get; set; }

    public decimal InstallmentAmount { get; set; }
}
/////////////////////////// with PLINQ  //////////////////////
foreach (var item in DC.Loans.Where(a => a.LoanType == 435).AsParallel())
{

 ParallelQuery<Installments> IList =
 CreateInstallmentTable(item.LoanNumber).AsParallel();
}