We're sorry to hear that you are unable to access your 2015 tax return.  If you used the free online version of TurboTax 2015, that may be the reason why.  In other words, one of the drawbacks to using our free online software is that prior year tax returns are generally not made available.  Free TurboTax users do have the option of saving or printing their own tax return at the time they prepare it, although this isn't always made clear in the program.

One choice to access your 2015 tax return, for an additional fee, is to add TurboTax Plus to your account.  That is described at the following TurboTax Frequently Asked Questions (FAQ) link:

https://ttlc.intuit.com/questions/2586262-how-do-i-add-plus-when-using-federal-free-edition

Another choice (and one that can be free) is to get what you need directly from the IRS itself (2015 tax return or tax data).  The following (2) links below will tell you how, and give you access to the IRS transcript / tax return request functions:

https://turbotax.intuit.com/tax-tools/tax-tips/IRS-Tax-Return/How-do-I-Request-Prior-Year-Federal-Ta...

For nearly all practical purposes, such as applying for a mortgage, showing proof of income to a landlord, or completing your following year tax return, the information you will receive from an IRS tax transcript is all that's necessary.

(Although to be absolutely 100% sure that a free IRS tax transcript, rather than a full tax return, will suffice for your particular mortgage company, you may want to ask them first.)

Generally speaking, however, only in a few cases is a full, duplicate, tax return absolutely required.  The reason this is mentioned and highlighted here in this discussion is that the IRS order transcript process is free, whereas there is a small fee to have a full paper copy of a tax return mailed to you by the IRS.  All of this is described and detailed on the pages linked to above; and when you get right to it, the IRS ordering process is really rather easy.

Ordering an IRS tax transcript might be a good (and free) way for you to proceed with your mortgage application.  The other alternatives would be to order a full tax return copy from the IRS (for a small charge), or to add TurboTax Plus to your online account (again, for a small charge).

Good luck to you; and thanks for asking this question.