The full amount of VAT can be reclaimed in respect of any valid business purchases - where the goods or services purchased are used purely for business purposes. In order to reclaim VAT, the business selling the goods or services must also be VAT registered, and should supply VAT invoices.
Business purchases which are also for personal use (eg a mobile phone contract which is used to make both business and personal calls) are only VAT deductible for the proportion of business use (eg if only 50% of calls are made for business purposes, only 50% of the VAT of the contract cost can be reclaimed).