NRIs are not eligible to fresh investment in Post offices.
If a depositor subsequently becomes NRI during the currency of the account, the account may be continued till its maturity on a non-repatriation basis. Such account shall not be extended beyond the maturity period, no interest shall be paid after maturity in such cases.
=CBS Manual Page 183
Presence of depositor at the time of opening of account is optional when any account is opened through Agent. If any account is opened through Agent by any person who is ineligible for opening accounts under National (Small) Savings Schemes like NRI or OCI Card holders or Non-Indian Citizens etc, such accounts will be treated as irregular and shall be closed without any interest. Commission paid to the Agent shall also be recovered.
*CBS Manual Rule No. 170, (18), Page No 274
Note : Scheme Interest eligible upto the date of citizenship changed. After that SB interest eligible upto Date of Closure.