You can continue to participate in the Common Good Plan, but you are not allowed to make additional contributions into the plan while you are not paying taxes in Canada.
It is your responsibility to ensure that you accurately characterize your residency status for tax purposes. If you are unsure about your status, you should contact the CRA or seek advice from a qualified professional. For further information, refer to CRA’s RRSPs and Other Registered Plans for Retirement, Guide for Individuals (T4040) or CRA’s Tax-Free Savings Account (TFSA), Guide for Individuals (RC4466).