Dear Shailender, there are 2 things
1) Reimbursements : - eg:- Out of Pocket expenses in an invoice of a chartered accountant - TDS is to be deducted on out of pocket expenses.
2) Expenses on behalf of others (Which will be claimed as reimbursements as above ):- eg:-Clearing & Forwarding agent makes the payment to Transporter on behalf of client - TDS is to be deducted on this amount also..
Can you please clarify on which subject you are talking that it is clearly mentioned in Singhania's Sir Book.??