In filing married separately, how do we separate charitable contributions, taxes, mortgage interest, etc. when payment is made with checks in both our names?

[xmasbaby0]

Are you in a community property state? ( Community property states:  AZ, CA, ID, LA, NV, NM, TX, WA, WI)

[xmasbaby0]

Why do you want to file separately--usually the worst way to file?  Do you have a good reason to file separately?

[Melalbert]

My wife incurred extraordinary medical expenses in 2018. NY not a community property state.

[xmasbaby0]

Not sure what that has to do with the choice to file separate returns.  See below.

[Melalbert]

You are right. It appears the incredibly high standard deduction far exceeds even our high medical expenses.

[Anonymous · Accepted solution]

Married, filing separately itemized deductions appears to be a complicated issue, but in reality it can be quite simple if you follow some basic rules.

First, the spouse who paid an expense - non joint account  that results in a tax deduction should claim the full deduction.

Second, In community property states, expenses paid with community property (a joint checking account) should be divided in half.

When married couples choose to file tax returns as married filing separately they report their own earned income and expenses on individual tax returns. In doing so, the married couple must agree how to best divide itemized expenses or choose to use the standard deduction to reduce their tax. The standard deduction is an amount that reduces the taxable income and eliminates the need to itemize tax deductions. Calculate both methods to decide which is most beneficial to you.

note that if One itemizes both must itemize.  

[xmasbaby0]

If you were legally married at the end of 2018 your filing choices are married filing jointly or married filing separately.

Married Filing Jointly is usually better, even if one spouse had little or no income. When you file a joint return, you and your spouse will get the married filing jointly standard deduction of $24,000 (+$1300 for each spouse 65 or older)  You are eligible for more credits including education credits, earned income credit, child and dependent care credit, and a larger income limit to receive the child tax credit. 

If you choose to file married filing separately, both spouses have to file the same way—either you both itemize or you both use standard deduction. Your tax rate will be higher than on a joint return. Some of the special rules for filing separately include: you cannot get earned income credit, education credits, adoption credits, or deductions for student loan interest. A higher percent of your Social Security benefits may be taxable.  In many cases you will not be able to take the child and dependent care credit. The amount you can contribute to a retirement account will be affected. If you live in a community property state, you will be required to provide additional information regarding your spouse’s income. ( Community property states:  AZ, CA, ID, LA, NV, NM, TX, WA, WI) If  you are using online TurboTax to prepare your returns, you will need to prepare two separate returns and pay twice.

https://ttlc.intuit.com/questions/1894449-married-filing-jointly-vs-married-filing-separately

https://ttlc.intuit.com/questions/1901162-married-filing-separately-in-community-property-states

https://ttlc.intuit.com/questions/1894449-is-it-better-for-a-married-couple-to-file-jointly-or-separ...