Asset Write off

Hi SAP gurus,

Can anyone help me on one scenario in asset accounting.. The user want to do the asset write off... and they want to change the rate of use.. there are 2 option that the user want:

1) Change the rate and do the write off exercise

2) Do the write off and then change the rate for remaining assets...

What kind of impact to the asset that will occur if either the 2 option being done... Thanks very much.. Your advice is much appreciated...

Thanks..

Nag.