Definition of 'Relationship Test'
One of several tests that a person must pass in order to be claimed as a dependent on someone else's tax return. The relationship test has several criteria, and as long as any one of them is met, the person in question is eligible to be claimed as a dependent by another. The relationship test mandates that the person in question must be either a lineal descendant or ancestor, sibling, in-law, niece, nephew, aunt, uncle or anyone other than the taxpayer's spouse who lived in the taxpayer's household during the entire year.
There is a separate relationship test to see if someone is a qualifying child (see below).
Investopedia explains 'Relationship Test'
The relationship test for a qualifying child mandates that the child be the taxpayer's child, stepchild, foster child, adopted child or any descendant thereof. Children who meet the criteria allow the taxpayer claiming them to receive their dependency exemptions. This test is one of four tests that a child must pass in order to be considered a qualifying child. The others are residence, age and support tests.