Sometimes a taxpayer will avoid filing their taxes for a decade. In that time, they have advanced their career, maybe even started a successful business. But then one day, they decide to purchase a home, and find that every mortgage lender they speak with requests proof of income and prior period tax returns.
This is a good opportunity to catch up both with the IRS as well as with your hopes of owning a home. Some CPAs will give you a break on price for the volume of multiple returns. Having those returns (signed by a license CPA) will strengthen your application. It may also be helpful to add a statement explaining the reason the return was filed late. There are several waivers available for late returns by the IRS.
I recommend to get started with the oldest return first, as you want your Net Operating Losses (if any), accumulated disallowed real estate losses (if applicable), accumulated depreciation, and all other carryover-type items to flow from one return to the next. For example, if you have unused Long Term Capital Gains, these can be carried forward to subsequent years.