(b) complies with the requirements of sub-paragraph (4) where relevant.  (a) in the case of a person who completed stage one—  (i) before 15th December 2020 and who is carrying out a test after 18th January 2021,  (ii) on or after 15th December 2020 and who is carrying out a test after whichever is the  later of—  (aa) 18th January 2021, and  (bb) the date four weeks after the date on which they completed stage one,  (b) in the case of a person who completed stage two—  (i) on or before 18th January 2021 and who is carrying out a test on or after 1st July  2021,  (ii) after 18th January 2021 and who is carrying out a test on or after whichever is the  later of—  (aa) 1st July 2021, and  (bb) the date four months after the date on which they completed stage two,  (a) P undertakes the test on or after the fifth day after the day on which P arrived in England;  (b) subject to sub-paragraphs (c) and (d), at the time the test is booked P notifies the test  provider that P wishes to undertake the test for the purposes of determining whether they  may cease self-isolating under these Regulations, and provides the test provider with—  (i) their full name,  (ii) their sex,  (iii) their date of birth,  (iv) their NHS number (if known and applicable),  (v) their ethnicity,  (vi) their home address, and the address or addresses at which they intend to self-isolate  in accordance with regulation 9 while in England (if different),  (vii) the date of their arrival in the United Kingdom,  (viii) their coach number, flight number or vessel name (as appropriate),  (ix) the date on which they last departed from or transited through a category 2 country  or territory,  (x) the country or territory they were travelling from when they arrived in the United  Kingdom, and any country or territory they transited through as part of that journey,  (xi) their email address,  (xii) their telephone number,  (xiii) their passport number, or travel document reference number (as appropriate);  (i) the notification and information set out in paragraph (b), other than in paragraph  (b)(xi) and (xii), is provided to the test provider on P’s behalf by another person  (“X”), and  (c) where P is a child, or a person with a disability who is unable for that reason to provide  the notification and information set out in paragraph (b) to the test provider—  71 (4) The requirements of this sub-paragraph are that—  they have complied with the requirements published by UKAS in relation to accreditation  to that standard at http://www.ukas.com/C19-Stage2-UKAS-Appraisal (“stage two”),  they are accredited by UKAS to that standard.  4.  The circumstances mentioned in paragraph 1 are that—  Required circumstances for undertaking testing 