A lot of DSCR lenders will ask for your tax returns, will check your credit score, will want to see that you have adequate reserves for a property, and will want to know how much experience you have and how many rentals you own.
They are not "no doc" loans. But the primary qualifications are the rental income for the property and credit score.
I've brokered for many, many lenders. Never once asked for a tax return.
