The agency overseeing business rates appeals has called in help from HMRC to resolve problems with its online portal.
It is understood that the Valuation Office Agency (VOA) has turned to HMRC as it faces mounting pressure from small business owners using the service.
The VOA’s three-stage “check, challenge, appeal” system for rates bills has attracted criticism since it came into effect on 1 April.
A spokesman for the VOA said: “The VOA’s check and challenge service is a new service that we are continuing to improve based on customer feedback.
”We are working closely with our customers and their representatives to understand and address any concerns, especially for businesses who own or occupy multiple properties.”
Drapers reported last month that property agents have been encouraging retailers to write to their local MPs to challenge the “unduly onerous and burdensome appeal rules”.