HMRC has recorded its best ever performance at collecting additional tax revenues through compliance work, but has admitted that its customer service levels are still not good enough, partly because of the extra work associated with the start of RTI.

Its briefing, How are we doing? HMRC's April to June 2013 performance, shows that the department brought in an extra £4bn over the quarter, including an additional £1.6 bn from VAT and more than £0.5bn from Corporation Tax.

However, HMRC handled just 77.6 % of all contact centre call attempts during the period, well below its 90% target. HMRC said this was due to a number of factors including 'technology-related issues', and the need to put extra people on the employer helplines to ensure strong performance during the introduction of RTI which saw more than 1.4m employers' and pension providers' PAYE schemes (around 80%) reporting in real time by the end of June.

HMRC revealed it decided to delay the introduction of new automated speech features on phone lines which it originally planned to bring in at this time, so it could answer more calls. These are now being trialled and will be rolled out later in the year.

The need to put extra staff on the phone lines also led to problems in handling post, HMRC has admitted. As a result, it missed its target of clearing 80% of post within 15 working days, managing to do so for only 70.3% of its mail.

HMRC says it is delivering 'significant training' to its operational teams to support flexible working. The aim is for staff to deal with customer enquiries in whatever form they come in, whether as a phone call, a letter or a work item generated by the customer records on its IT system, and HMRC says it expects to see performance in this area improve throughout 2013-14.