BIM46975 - Specific deductions: repairs and renewals: change to valuation basis
From capital allowances to valuation basis
Where a request is made for a change from capital allowances to valuation basis and the assets are such that valuation basis is appropriate (see BIM46970), the capital allowances written down value can be accepted as the opening figure for the valuation basis.
From renewals allowance to valuation basis
Valuation basis cannot apply to expenditure on assets which has been relieved by renewals allowance. However, you can accept a claim for future assets to be dealt with under the valuation basis, provided that basis is appropriate to the class of asset (see BIM46970).