GOV.UK
Opening and Working Enquiries: NTC information power not to be used to obtain information for an SA enquiry
The information power at S19(2) TCA is less restrictively worded than the SA information power at S19A TMA 1970. If you are involved in, or liaising on, an SA enquiry into the return of a taxpayer who is also a tax credits customer, you may be asked to use S19(2) TCA to obtain some information for the purposes of the SA enquiry. You must not do this. S 19(2) TCA must only be used to obtain information for the purposes of your tax credits enquiry, and you must be scrupulous in ensuring that you use it in this way. You should note that S19(A) TMA does not have its own third party information power, and you should take particular care to avoid using the third party powers at S19(2) TCA for anything other than tax credits purposes.
Once you have obtained the information for the purposes of your tax credits enquiry, you can pass it on to other HMRC officers, including those dealing with the customer’s SA if appropriate. But you must not ask for the information in the knowledge that the real reason you want it is for purposes other than tax credits, e.g. for an SA enquiry.