If your Margin Funding expires and your Margin Trading position remains open, the system will automatically reserve the appropriate Margin Funding at the current available rate.
When the Margin Funding used for your active Margin Trading position expires, the platform will always use any manually reserved Margin Funding first, and if necessary, will automatically fill the remainder with the current prevailing rate available.
Note: You can manually reserve Margin Financing through the Funding page before your existing funding expires if you want more control over the rate and period.
If you have any questions, please feel free to reach out to Bitfinex Support. We are happy to help!