Tax Penalty/Bonus? – Single, Married, Domestic Partnerships

After nearly thirty years of marriage, I would be the last person to suggest that
tax consequences are a reason for making a lifelong personal commitment. On
the other hand, I am often the first to point out that marriage is not always a
tax neutral activity. Some people work on the expectation that a “married
filing jointly” (or MFJ) tax filing will always result in a lower combined tax
liability and a marriage tax bonus (meaning taxes are reduced solely due to
filing as MFJ). They are surprised when this joint filing actually creates a
marriage tax penalty (meaning filing MFJ results in higher taxes).

So when should we expect a penalty or bonus? The literature describes that ‘in
general’ we see a tax bonus when two partners have disparate incomes and a
tax penalty when they have similar or equal income. Based on the literature I
expected that income splitting (as occurs in a domestic partnership tax filing)
could provide an additional tax bonus over MFJ since disparate incomes can
be split evenly between partners.

While exploring the new 2013 tax rules we examined some tax scenarios and
want to share some highlights with you. We found that starting at a combined
AGI (Adjusted Gross Income–the number at the very bottom of the 1040
form) of $230K filing as MFJ resulted in a tax bonus of about $2K IF the two
people had disparate incomes ($200K and $30K respectively) but a penalty of
$2K for those with similar incomes ($115K each). Therefore at this level of
AGI couples with disparate incomes do slightly better under MFJ and those
with similar AGI do slightly better filing as individuals.

With a joint AGI of $330K the single disparate earners ($300K and $30K)
receive a marriage tax bonus of about $3K. If the same joint income was
earned evenly ($165K each) they would pay $4K more filing as MFJ than as
two individuals (a $4K tax marriage penalty). Looking at these scenarios, it
became clear that those with similar incomes would annually save thousands
of dollars if they filed as individuals rather than MFJ (Note: this is not the
same as married filing separately but rather unmarried individuals). As a
corollary, those in a domestic partnership may want to verify that they will not
have a large tax increase if they marry and file as MFJ.

Finally we looked at a couple with a $530K AGI who will pay $143K in taxes if
they file as two individuals with disparate incomes ($500K and $30K) and
taxes will be about the same if they file under MFJ (there is about a $1K tax
bonus). We do see a large tax penalty if this income was earned evenly by two
individual filers ($265K each) and they file MFJ. As two individuals the tax
burden would drop by at least $15K.

Marriage does provide non-income tax related advantages for spouses and
the family which are not discussed here.

Once you consider tax consequences of marriage, domestic partnership or
single tax filings any decision you make will work as long as you make plans to
cover the marriage tax penalty or find ways to spend the marriage bonus.
The above analysis assumed that ‘itemized deductions’ were kept constant and
that there was no AMT. These were modeled tax estimates – please consult
your tax preparers for the specific tax impact in your situation.