If I understand the situation, it is like this
1. Date of resigantion: 15th May 2012
2. Date of relieving: 14th June 2012
3. On leave from: 20th May 2012 to 9th May 2012
4. Will join duty on: 10th June 2912
5: Will get relieved on: 14th June 2012
I these facts are correct, he has given notice for one month and he has availed 20 days levae in between duly authorised by you.
If he has leave to his credit, then treat this leave with pay and you must pay his salary. You also have taken notice from him on 15th May and you are relieving him on 14th June. That means. you can not decduct any amount towards notice period as he has served 30 days notice on you.
If the employee does not have leave to his credit, then treat the period as loss of pay. Even then, he has given you notice for 30 days and you can not deduct any amount towards notice pay.
If he has remianed absent and gone without obtaining prior approval, then do not allow him to join on duty on 9th . If you have sent communications stating that he is remaini ng absent, and he will be deemed to have gone without notice, then you can dedcut notice pay.
But if he heas remained absent and if you have allowed to join back on 9th June, it will deemed that you have condoned his absence and no adjustment on notice period can be made. However you do not need to pay salary for the period of absence
Sivasankaran