MAGI is calculated when you prepare your tax return. What you are concerned about instead is changes to the income that you estimated on your insurance application. You are to report changes in your estimated income on your insurance application as soon as possible after the estimate changes. If not already included in your original estimate of your annual income, you would need to report the update to your estimate upon doing the In-plan Roth Rollover since that income would be locked in at that point (absent the inadvertent rollover of some amount that was ineligible for rollover).
