Department issued communications advising traders not to travel to ports while services were impacted
HM Revenue and Customs missed an estimated 100,000 calls during five days of web and helpline outages that ended earlier this week, the department has revealed.
Various online and telephone services provided by the department began suffering disruption from 8am on Thursday 1 December. Issues continued throughout last weekend and were not entirely fixed until 10.30am on Monday 5 December, according to HMRC chief executive Jim Harra.
The problems are thought to have been caused by a high volume of online traffic that resulted from “a change we had introduced overnight on Wednesday 30 November [that] had altered the digital traffic management profile on our IT infrastructure”, the CEO wrote, in a letter to parliament’s Treasury Committee.
The most badly impacted service was NCTS, which is used by traders to electronically submit international transit declarations.
Once it became clear on Thursday morning that “NCTS was unable to process the volume of declarations it was receiving”, HMRC activated a contingency plan which “included issuing communications advising customers who had not started their journeys not to travel to ports or Inland Border Facilities and detailing steps to take for those who were already on their way”.
The department also put in manual “workaround procedures” to help clear the backlog of declarations.
To allow for sufficient resources to be dedicated to addressing the NCTS issues, the tax agency also decided to temporarily shut down web services for employers to manage their PAYE commitments. This online income tax platform was reopened the following morning.
All telephony helplines – other than the service for supporting traders with customs clearances – were also closed on Thursday morning.
These remained offline until after weekend, and were “gradually” reopened between 8am and 10.30am on Monday 5 December.
During this time frame, Harra told MPs that “would normally have expected to handle around 99,000 customer calls” across the various telephone support services.
The closure of the helplines and the PAYE online service did have the desired effect though, enabling “reduced digital traffic on our IT infrastructure, [with] NCTS fully restored by 4pm on Thursday 1 December”, the CEO added.
The traffic management change that caused the issues was rolled back at about 1pm last Friday, after which the department “saw service performance improve and stabilise. HMRC undertook “further housekeeping on our IT infrastructure” at 8pm that evening, according to Harra.
“Services continued to perform well over the weekend, albeit with lower volumes of users and digital traffic than on weekdays, and with our telephony lines closed,” he added. “Throughout the incident, most of our customer-facing online services, such as Self Assessment online filing, were unaffected and remained available to users.”
The CEO told the committee that “we will be carrying out a review of lessons from this incident”.