Qualified property must be either originally used or substantially improved to meet the 90% (at QOF level) or 70% (at QOZB level) tests. When a QOZB is used, the requirement for original use or substantial improvement must be met by the QOZ business. The final regulations solidify that land can more easily meet the original use test with limited improvements, that leased property is exempt from the original use/substantial improvement tests, and that there are various aggregation concepts that can be deployed when analyzing original use/substantial rehab amongst a similar category of business assets.