The corporate income tax adjustment covers prior years up to 26 September 2015, according to the accounts Apple has filed for the 18 months to April 2017, and as a result the company says it expects to pay more corporate tax going forward.

Apple UK provides sales, marketing and technical support services to another Apple company. HMRC is believed to have argued that the subsidiary had not received a large enough commission on the sales it helped secure. It reported pre-tax profits of £291.7m and a total tax bill — including the extra £81m — of £117m.

Miles Dean, managing partner of Milestone International Tax, said: ‘HMRC has scrutinised the intra-group arrangements and concluded that the price paid for services was not what unconnected third parties would have agreed to pay for those same services.

‘The issue here is transfer pricing – the UK has a set of rules based on international standards that apply to transactions between related parties. Basically, transactions between related parties must be on the same terms as those that unconnected parties would agree.

‘The main difficulty for the tax authorities is proving that the price paid is the right one – this is often very subjective and from HMRC’s point of view, very time-consuming and under resourced.’

Apple handed over the additional £81m to HMR after an ‘extensive audit’, in the latest of a series of claims against the company which has also been required to set aside €13bn (£11.5bn) to pay a disputed bill for back taxes that the EU says Apple owes in Ireland.

Report by Pat Sweet