1) Set the tax Codes to be Uses in iExpenese
Payables - > Setup- > Tax - > Codes
2) Set the Hierarchy for Tax Code Defaulting
Payables - > Setup- > Options - > Payables
Here template mean expense template .
3) For Project based expenses set the Expenditure type to be used in iExpense
Project ->Setup - >Expenditures - > Expenditure Type
To use a expenditure type it has to be assigned to Expenditure type class of "Expense Reports"
4 ) Payables Manager: Setup > Options > Financials
Expense Clearing Account ->This will be a default liability account for iExpenses expenses reports imported into Oracle Payables