https://www.slab.org.uk/guidance/cover-for-work-done-before-a-decision-on-the-legal-aid-application-the-nature-and-types-of-special-urgency/
Depending upon the circumstances, and the type of urgent work you need to do, you may:
If you have approval to do work as a matter of special urgency to protect your client’s position, any legal aid that we subsequently grant will include that work.
Where the special urgency provisions are being used you must tell us and submit an application for legal aid including all the craves for work you want to do within 28 days of starting the work. You must tell us that you have done the work under regulation 18(1)(a) at the same time as you apply for civil legal aid. If you have already submitted an application you should use a special urgency notification. If you do not, the work will be excluded from any legal aid that may be made available.
If you are applying for approval under regulation 18(1)(b), you should submit a special urgency application. If we grant approval, we may limit the work or subject this to conditions, as we consider appropriate. While you do not need to notify us that work has actually been done following approval, you must ensure you have submitted a legal aid application within 28 days of beginning the urgent work. If you do not, the work will be excluded from any legal aid that may be made available.
Where work has been done in accordance with regulation 18, that work is covered under the legal aid subsequently granted. This does not mean the effective date on the certificate must be put back to the date the urgent work began. Your entitlement to payment depends on compliance with the terms of regulation 18 and not on any effective date stated on the certificate.