Substantial Improvement Test
A Qualified Opportunity Fund that buys an existing building must generally double its basis in the building within 30 months.
Nashional Investments · Updated October 2026
Educational definition only, not investment, tax or legal advice.
In practice
Opportunity Zone rules turn on timing: when the gain was realized, when it is reinvested, and how long the fund investment is held. Understanding Substantial Improvement Test matters because it can affect how much gain is deferred or excluded. The rules for investments made from January 1, 2027 differ from the original program, so we check which regime applies before recommending a Qualified Opportunity Fund.
Common questions.
What does the term Substantial Improvement Test mean?
Why does Substantial Improvement Test matter for investors?
See how this fits into a real plan on our Opportunity Zones page.
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