https://www.slab.org.uk/guidance/special-urgency-satisfying-yourself-that-a-client-is-financially-eligible/
You should refer to the guidance on declaration and verification. Our view is that you will usually only be able to be satisfied as to financial eligibility when you have seen documentary evidence to support this. Providing the signed declaration and financial verification will also assist SLAB to determine the application accurately and efficiently, to properly pay your account as well as undertake any later quality assurance checks, including peer review.