The Hidden Trap in Planning Time Extensions After April 2026

If you have a planning application with a council right now, or you are about to submit one, there is a strategic decision you need to understand before 1 April 2026. It concerns time extensions — those routine requests from councils asking you to agree to extend the statutory determination period. Most applicants agree without thinking. After April, that decision carries real consequences.

Here is the background. When you submit a planning application, the council has a statutory deadline to make a decision — 8 weeks for most applications, 13 weeks for major developments. If the council cannot decide within that period, they will often ask you to agree to an extension of time. This is common practice, and historically it has been a neutral administrative decision.

From 1 April 2026, it is no longer neutral. The new appeal rules create two distinct procedures. Part 1 is the expedited written representations procedure — it is faster, but crucially, no new evidence can be submitted at appeal. Part 2 allows fuller evidence exchange, including new documents and expert reports. The question of which procedure applies to your appeal depends in part on whether you agreed to a time extension.

The mechanism works like this. If your application is refused after the statutory deadline has passed, you can appeal on grounds of non-determination — the council failed to decide in time. Non-determination appeals follow the Part 2 procedure, which preserves your right to submit new evidence. However, if you agreed to extend the deadline and the council then refuses your application within that extended period, your appeal follows Part 1. No new evidence.

This creates a genuine strategic dilemma for applicants on difficult sites. If you believe refusal is likely — perhaps because of officer feedback, committee dynamics, or unresolved policy conflicts — agreeing to a time extension could be the worst thing you do. By agreeing, you give the council more time to formalise a refusal while simultaneously restricting your own options at appeal.

The alternative is to let the statutory deadline expire without agreement. This feels confrontational, and many applicants are reluctant to do it because they worry it will antagonise the council. But the legal position is clear: if the council has not decided within the statutory period and you have not agreed an extension, you have the right to appeal for non-determination under Part 2, with full evidence rights preserved.

There are important nuances. First, this only applies to applications submitted on or after 1 April 2026. Applications submitted before that date follow the previous rules regardless of when the decision is made. Second, some application types — major developments, EIA applications, cases of significant public interest — may qualify for Part 2 regardless of time extensions. Third, the decision to refuse a time extension should not be taken lightly — there are cases where the extra time genuinely helps, particularly if officers are supportive but need more time to resolve technical consultee responses.

The key is to make this decision deliberately rather than reflexively. Before agreeing to any time extension after April 2026, you or your planning agent should assess three things. First, what is the realistic likelihood of approval? If officers are supportive and the extension is to finalise conditions, agree. Second, if refusal is possible, what new evidence might you need at appeal? If you might need to commission additional surveys, assessments, or expert reports, preserving Part 2 rights could be critical. Third, is your original application strong enough to stand on its own at appeal? If your reports are comprehensive, evidence-based, and policy-compliant, Part 1 may be perfectly adequate.

This is exactly why the quality of your original submission matters more than ever. If your planning application is genuinely appeal-ready from day one — every constraint addressed, every policy cited, every data source current — then the Part 1 procedure is not a trap. It is simply a faster route to a fair hearing. The trap only closes on applications that were submitted with gaps, hoping those gaps could be filled later.

Our strong advice: do not agree to a time extension on autopilot. Treat it as a strategic decision. Discuss it with your planning consultant. And if there is any chance your application may be refused, make sure your original submission is strong enough to stand on its own — because under the new rules, it may have to.