My 65 year old daughter is collecting her cpp payments and also worked part time in 2018. cra wants the dates she requested to stop cpp contributions and the date she revoked her cpp,how is this done?/
She would of had to complete form CPT30, Election to stop contributing to the Canada Pension Plan, or Revocation of a Prior election. When this form is completed she had to give a copy to her employer - then send the original to CRA- Which then the "election" chosen to either stop contributing or revocation will take effect the 1st day of the following month- that she gave the copy to your employer.
Your daughter should have a copy of the CPT30 which has the date on it. - Which would show the date she wanted to stop contributing to CPP- then one that showed (revoking) wanting to continue to pay CPP.
If you need more help- please contact CRA directly so that they can assist you- https://turbotax.community.intuit.ca/replies/2647704