Council AI planning checker cuts waits by half but wrongly rejects one in 20 applications

An artificial intelligence tool that checks planning applications for missing documents before a human officer sees them has halved the time taken to validate submissions at 12 English councils but is rejecting about one in 20 valid applications in error, according to an evaluation published on Monday by the Ministry of Housing, Communities and Local Government.

The tool, built in-house by the ministry’s digital planning unit, reads uploaded drawings, forms and reports and checks them against each council’s list of required documents. It has processed 41,000 applications since January at councils including Wakefield, Bromley, Plymouth and South Norfolk. Average validation time fell from 19 working days to nine, and the backlog of unvalidated applications across the 12 councils fell from 6,100 to 1,900.

But the evaluation found that 5.2% of applications rejected by the tool had in fact contained everything required. The most common errors were a failure to recognise site plans where the red line had been drawn in a non-standard colour, and the misreading of scale bars on hand-drawn elevations, which remain common for small householder extensions.

“Nine days instead of 19 is real and it matters to people waiting to build,” said the ministry’s head of digital planning, Rachel Oyinlola. “A 5% false rejection rate is not acceptable and we have been clear with councils that a human must look at every rejection before it goes out. Where that has not happened, it is because of workload, and that is the problem the tool exists to solve.”

Complaints have risen. The Local Government and Social Care Ombudsman said it had received 84 complaints about planning validation in the trial areas since January, compared with 31 in the same period last year. Several involved applicants who were charged a £70 resubmission fee after an automated rejection.

Dev Ramanathan, 39, who applied in May to extend his terrace house in Wakefield, was told three times that his site plan was missing. “It was there. It was the first document in the upload,” he said. “The third time I rang up and a very nice woman looked at it for about four seconds and said it was fine. That cost me seven weeks and £140.”

The Royal Town Planning Institute said the tool was addressing a genuine bottleneck: councils have lost about a quarter of their planning staff since 2010, and validation is work that trained officers resent. But its policy director, Hugh Marchbanks, said the ministry should publish the error rate for each council. “Some of these authorities are checking every rejection and some, frankly, are not,” he said.

The ministry intends to offer the tool to all 317 English planning authorities from April. It said the next version, trained on a further 60,000 applications, had cut the false rejection rate to 2.1% in testing, and that applicants would no longer be charged for resubmission after an automated rejection that is subsequently overturned.