To use the Interest Only rate after the IO period expires you can:
Input your Interest Only rate and the remaining P&I loan term in years
Leave the IO Term section blank to avoid triggering the calc in taking the revert rate after IO expires
Please keep in mind, most banks uses the revert rate after the IO period in assessing existing home loans in their serviceability calculator so we highly suggest following this process to be in line with the bank's policy and for accuracy of results.
If you have any questions reach out on the chat box in the bottom right hand corner of your screen 🤓