Means the amount against Govt. has been recovered by the IT dept by setting off the Dues/arrears recoverable, against any refund due to the assessee.........

How do we come to know that from which year's demand the refund is adjusted??

The intimation regarding refund adjusted has been sent to your mail a/c...

you can also call up CPC, collect the information from them.

Check out your records, if you find any discrepancy in such adjustment, contact your local AO.

Try sorting out at the earliest, b'coz  the future refunds also will be adjusted, if demand still exists.