Changing intention of type of Hajj

Question: If a person intends to perform Qirān at the Mīqāt, and then upon reaching Makkah changes the intention to Tamattu', or vice versa, is this permissible?

Answer: If a person changes the intention before completing four circuits of the Ṭawāf, then it is permissible to change from Qirān to Tamattu' or from Tamattu' to Qirān. Both forms of Hajj will be valid, although changing the intention in this manner is contrary to the Sunnah and therefore not preferable.

Similarly, if a person entered into Ihrām for Ifrād and then changes to Tamattu' or Qirān this is also permissible, although not preferable.

This ruling applies provided the change is made before completing four circuits of the Ṭawāf of 'Umrah.

References:

Mu'allimul Ḥujjāj, p.245

Fatāwā Dārul 'Ulūm Zakariyyā, vol. 3, p.406

Ḥajj Masā'il for Women by Mufti Farooq Sahib