In-house testing or calibration laboratories shall comply with the IATF16949 – §7.1.5.3.1 requirements, that repeats the ISO / IEC 17025 requirements. Either the laboratory demonstrates compliance with the requirement through third party accreditation or it demonstrates compliance with ISO / IEC 17025.
For external laboratories, the IATF sanctioned interpretation #10 of April 2021, requires evidence that the testing or calibration laboratory has been assessed and complies with the §7.1.5.3.2 requirements, i.e. that compliance with ISO/IEC 17025 is established through an internal or 2nd party audit.