LedgerSMB does not have a built-in assett tracking / depreciation feature. Depreciation can be managed manually using General Ledger Transactions. You should probably confirm this with your accountant, but the basic procedure (kindly suggested by Tony Fraser) is, assuming a computer asset over 5 years:

Set up 3 accounts:

• An asset account such as "Computers"
• An asset account such as "Accumulated Amortization, Computers" that is normally a negative balance therefor it is a contra account
• An expense account such as "Computer Depreciation"

Upon purchasing a depreciable asset (in this case, a computer):