You can include only the medical and dental expenses you paid this year, regardless of when the services were provided. (But see Decedent
under Whose Medical Expenses Can You Include,
later, for an exception.) If you pay medical expenses by check, the day you mail or deliver the check generally is the date of payment. If you use a "pay-by-phone" or "online" account to pay your medical expenses, the date reported on the statement of the financial institution showing when payment was made is the date of payment. If you use a credit card, include medical expenses you charge to your credit card in the year the charge is made, not when you actually pay the amount charged.
If you did not claim a medical or dental expense that would have been deductible in an earlier year, you can file Form 1040X, Amended U.S. Individual Income Tax Return, for the year in which you overlooked the expense. Do not claim the expense on this year's return. Generally, an amended return must be filed within 3 years from the date the original return was filed or within 2 years from the time the tax was paid, whichever is later.
You cannot include medical expenses that were paid by insurance companies or other sources. This is true whether the payments were made directly to you, to the patient, or to the provider of the medical services. taxmap/pubs/p502-001.htm#en_us_publink100014759
If you and your spouse live in a noncommunity property state and file separate returns, each of you can include only the medical expenses each actually paid. Any medical expenses paid out of a joint checking account in which you and your spouse have the same interest are considered to have been paid equally by each of you, unless you can show otherwise. taxmap/pubs/p502-001.htm#en_us_publink100014760
If you and your spouse live in a community property state and file separate returns, any medical expenses paid out of community funds are divided equally. Each of you should include half the expenses. If medical expenses are paid out of the separate funds of one spouse, only the spouse who paid the medical expenses can include them. If you live in a community property state, are married, and file a separate return, see Publication 555, Community Property.