After carefully checking the power of attorney to make sure that it accurately reflects his or her intentions, the donor should sign it before a person authorised by law to take affidavits. This means a lawyer, a justice of the peace, or a proclaimed police officer.

The donee of an enduring power of attorney must sign the form to show that she or he agrees to accept the responsibility of being a donee. The wording used for the acceptance must comply with the wording in Schedule 2 of the Powers of Attorney and Agency Act 1984 (SA). This is the wording on the official 'Enduring Power of Attorney' form. Although it is not a requirement that the donor and donee sign at the same time, it is advisable for the donee to sign within a reasonable time after the donor's signature has been witnessed, as this will avoid complications later if the donor suffers an incapacity.