how do banks calculate income for an existing rental

[David Mirza]

I understand that for a Fannie Mae conventional loan, if you don't have tax returns for a rental, most lenders will count 75% of your rent as income and the full PITI as your debt. The part where I'm not clear on is for an existing rental where tax returns are available.

I know that Principal, Interest, and taxes are all included as debt.  Depreciation is not counted as an expense.  What about one time repairs like fixing a leaky roof?  How about expenditures that are depreciated over 7 years like a new fridge?