Alimony is a payment to or for a spouse or former spouse under a divorce or separation instrument. It does not include voluntary payments that are not made under a divorce or separation instrument.
Alimony is deductible by the payer, and the recipient must include it in income. Although this discussion generally is written for the payer of the alimony, the recipient also can use the information to determine whether an amount received is alimony.
Note. Amounts paid as alimony or separate maintenance payments under a divorce or separation agreement executed after 2019 won't be deductible by the payer. Such amounts also won't be includible in the income of the recipient.
For more information on these requirements, please refer of IRS Publication 504 Divorced or Separated Individuals.