Expenses drive everything the plan has to fund. You can enter simple annual totals or itemise by category, and set separate figures for working life and retirement.
Your expenses drive the whole plan, because they're what your income and savings have to cover. You enter them in the Your Facts tab under Expenses. You have two choices. The simple way is to enter one annual figure for your spending while working, and one base figure for retirement. Or you can turn on the itemised breakdown and enter your spending category by category — housing, food, travel, and so on. One important tip: don't include mortgage payments here, because those are handled separately on the Property tab. Your retirement figure is a base that the app then shapes into three phases — more active early years, a settled middle, and later life with possible care costs, which you'll see on the Longevity tab.