IRS FATCA Registration FAQ12 provides the following guidelines on the FFI renewal deadline extension.

Participating FFIs (including Reporting Model 2 FFIs) that have otherwise complied with the terms of the FFI agreement (including, since January 1, 2017, the current FFI Agreement) have until October 24, 2017, to renew the FFI agreement and continue to be treated as a participating FFI.

If an entity that is required to renew the FFI agreement does not renew the FFI agreement by October 24, 2017, the registration status of the entity will be changed to “incomplete,” the entity’s GIIN will no longer appear on the monthly FFI List beginning in November, and the entity will be considered a nonparticipating FFI as of January 1, 2017, as provided in section 3.02 of Revenue Procedure 2017-16.

https://www.irs.gov/businesses/corporations/frequently-asked-questions-faqs-fatca-compliance-legal

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