review of useful life of assets at the end of each reporting period

Thank you - yes - it was a really nice break! IAS 8 deals only with accounting for CHANGES in accounting estimates - it states only in very general terms "An estimate may need revision if changes occur in the circumstances on which the estimate was based or as a result of new information or more experience." Other, more specific, IASs deal with the making/reviewing of accounting estimates e.g. IAS 16 requires residual value, useful life and depreciation method to be reviewed "at least at each financial year-end".