Father who filed jointly with mom on previous year and is now my dependent.

[rtaxc]

I'm claiming my dad as a dependent, but the previous year he was on my mom's joint return.

I have paid well over 50% of the support for my dad and he only has SS income and less than $200 of interest.

They had a refund for that joint filing year which they applied to the next year.  My mom also made estimated payments for the year that I'm claiming my dad as a dependent.  The year I am claiming my dad as a dependent, my mom will file as a single taxpayer.  They are still married.  Since their previous year refund is half my dad's should I claim dad's half of the refund on the return that I am filing with him as a dependent or should my mom claim all of the refund plus all of the estimated payments?   Also my parents had a joint Edward Jones account (although it is reported to IRS to my mom's SS#) 

I assume I should report all of my dad's income on my return if I am claiming him.

What do I do about the refund for the previous year that my parents had applied to the year that he becomes my dependent?

Also should I claim half of the Edward Jones income or let my mom claim all of it on her return?

[VolvoGirl]

No.  You do not report a dependent's income on your return.  It only goes on their return.  And you mother can not file Single.  Only as MFS Married Filing Separately.

You  have several issues I don't know.  Someone else will have to reply.  Just wanted to clear up those 2 points.

[pk]

adding to @VolvoGirl  reply --- (a) your mother ( father's spouse ) needs to file as MFS ( Married Filing Separate ) showing her independent income(s) ; (b) your father needs to file MFS, showing his independent income(s) and declaring that someone can claim him as a dependent ;  (c) you file under your usual filing status  and claiming your father as dependent -- note however, that by doing this  you do not get his personal exemption ( it is ZERO for the years 2018 through 2025 ) but you may impact his standard deduction for being a dependent of another;  (d) depending on the state your parents reside in there may be "income split" required  between the spouses;  (e)  even if the  Edward Jones shows your mother's SSN as primary , if it is jointly owned  then  its income(s) may have to be shared , depending on the laws of the state they reside in.

As you can see from the above, before you decide to claim your father as your dependent, you need to  be clear about  what you are trying to achieve.  If all you are trying to get credit for is the financial support you provide them ( and if they live together  and depending on the state they live in ) , you may or may not achieve much.  Suggest discussing  this with a tax professional -- this may cost you a bit  but definitely will guide  you in achieving the best results under the current laws

Good Luck 

[rtaxc]

Basically I would like to be able to deduct my expenses for supporting my dad's stay in a nursing home, which are significant.  My parents and I live in Colorado and my parents live apart.  This is for 2015 not 2018

[Hal_Al]

You do not report your dependent's income on your tax return. You also do not get to take credit for your dependent's refund  (or withholding or estimated payments) on your tax return.  Your mother gets full credit for that on her return, since your father (apparently) will not be filing a return.

If your father qualifies as your dependent (and its not clear that he does), you may deduct most of his nursing home costs as medical expenses. Medical expenses are only deductible as an itemized deduction, subject to a 7.5% of AGI threshold. 

You should not be claiming your father as a dependent until you and you mother have prepared comparative returns to see which way the family comes out best.  By forcing your mother to file as Married Filing Separately (MFS) (instead of Married Filing Jointly (MFJ) ), she will almost assuredly lose more than you gain. You can use this tool: https://turbotax.intuit.com/tax-tools/calculators/taxcaster/?s=1

The brokerage account further complicates things, even though it's in her name an SS#, your father may be responsible for reporting half the income.

[Hal_Al]

" This is for 2015 not 2018".

What does that mean?  You (and/or your parents) never filed a 2015 return or you want to amend?  If your parents file a 2015 return as MFJ, they are not allowed to amend to MFS.  

You cannot claim a refund after 3 years  (but you can file a return and/or pay).

[rtaxc]

Actually you have until 3 years PLUS extensions to claim a refund.  In this case we have until October 15, 2019 to file for refunds.