What should I choose on the "Natural Income" page of applications?

This is at your discretion, but it is worth noting if you select "reinvest" where the client in invested in model portfolios containing income funds or cash, that any income distributions generated (or cash interest generated) will rebuy the model.

Note that there are certain processes that cannot be completed whilst assets in a model are trading (e.g. crystallisations) until that model trade has settled so you should consider choosing "Leave as cash" if you are looking to minimise model trading.