Most applications do not fail. They stop.

The dates that end cases

Twelve months from a provisional to a complete specification. Twelve months from first filing for convention or PCT filing. Thirty-one months for national phase entry. Thirty-one months (for filings from 15 March 2024) or forty-eight months (for earlier ones) for the examination request. Six months, extendable by three, from the first examination report. Renewal fees, from the expiration of the second year.

Each has its own extension rules, and they are not the same.

What the 2024 rewrite did and did not do

Rule 138 was replaced with a provision allowing the Controller to extend time or condone delay by up to six months on a request in Form 4, made within that six-month window, and it may be made more than once inside it. On its face it has no carve-outs, which is a significant change from the earlier one-month version with a long exclusion list.

But whether it actually reaches the examination request, the FER period and national phase entry is not settled, sources conflict, and at least one recent decision points the other way for national phase. Treat those three as unextendable and use the specific extension provisions - Form 4 under rule 24B(6) for the FER period, and rule 80(1A) for renewals - where they exist.