How to Import Lease Data into CoStar Real Estate Manager

To import lease data into CoStar Real Estate Manager, abstract each lease into structured fields, arrange them in a spreadsheet that matches your CoStar import template, and load the file through the platform's data import tool. The two things that make rows reject are dates that were never separated cleanly and a rent schedule that does not reconcile to the lease, so both are worth catching before you load.

CoStar Real Estate Manager is the system of record a corporate real estate team uses to run lease administration and ASC 842, IFRS 16, and GASB 87 accounting. It does not read your leases for you at import time. Every schedule, journal entry, and critical-date alert it produces comes from fields that someone abstracted out of the lease first. Getting those fields right, and in the shape CoStar expects, is the whole job. Here is how to do it without a stalled migration.

What CoStar Real Estate Manager needs before you import

CoStar lets each customer define the fields it captures and add unlimited custom fields, so the exact column list depends on your instance. The core set, though, is always the same, because it is what the accounting engine runs on:

• Possession, commencement, and rent start dates. These have to be separate values. A lease that hands over possession weeks before rent starts will produce the wrong schedule if the two dates are collapsed into one.
• The full base rent schedule. Every step, escalation, and free-rent period, period by period, so the amortization CoStar builds matches the document.
• Options and their notice dates. Renewal, termination, expansion, and purchase options, each with the window in which notice must be given.
• CAM and recovery terms. The recovery method, base year or expense stop, any caps, and the tenant's pro rata share.
• Property and unit identifiers. The building and suite codes that let CoStar attach the lease to the right location.

Step 1: Abstract each lease into the CoStar fields

This is the part that decides whether the import goes smoothly. Read each lease and its amendments and pull the fields above into a clean record. The failure mode is subtle: an abstract that looks complete but has a rent step keyed to the wrong month, or a renewal notice date copied from the option term instead of the notice window. Because CoStar runs calculations on these values, a small error becomes a wrong schedule, not a typo you notice later. Abstracting to a format where every field cites the lease page it came from lets a reviewer verify the rent steps and option dates in minutes rather than rereading the document. You can do that abstraction with CoStar lease abstraction free before you commit to any managed service.

Step 2: Map your fields to the CoStar import template

Once each lease is abstracted, arrange the data in a spreadsheet whose columns line up with your CoStar import template. The headers have to match what your instance expects, and dates need a consistent format across every row. If your CoStar setup uses custom fields, add those columns and fill them from the abstract. Keep the property and unit codes exactly as they appear in CoStar, because a code that does not match the location master is the most common reason a row is rejected on load. A large scanned portfolio often arrives as a stack of PDFs, and getting those into a working spreadsheet is easier when you can run the automated document data extraction on the non-lease paperwork that comes with them.

Step 3: Load through the data import tool and validate

CoStar Real Estate Manager includes a built-in data import tool with audit-ready controls. Load your mapped file, then check the import log for rejected rows and validation warnings. Validate the loaded data against a handful of leases you know well: confirm the commencement date, the first and last rent steps, and one option notice date on each. If those tie out, the mapping is sound and the rest of the batch is trustworthy. If they do not, fix the abstract or the mapping, not the record inside CoStar, so the source of truth stays the lease file.

What makes a CoStar import reject

Two problems account for most stalled loads. The first is dates that were never separated, so possession, commencement, and rent start collapse into one value and the schedule starts on the wrong day. The second is a rent schedule that does not reconcile: a missing step, a free-rent month left out, or an escalation applied to the wrong period. A unit or property code that does not match the CoStar location master is the third. All three are caught before import if the abstract is source-linked, because the reviewer sees the value next to the clause it came from and spots the mismatch immediately.

Can you use AI to speed up abstraction for CoStar?

Yes, and abstraction is the slow part of a CoStar rollout, so it is where AI helps most. An AI abstraction tool reads each lease and returns the CoStar fields as structured data far faster than keying them by hand, and a good one cites the source page for every value so review is verification rather than re-entry. CoStar itself offers a managed human abstraction service and, through Visual Lease, an AI engine powered by its Lease LLM, but both are sales-led. If you want to test the output on your own worst-scanned lease first and export a CoStar-ready file yourself, abstract a lease for CoStar free with the tool at the top of the page.

How long does a CoStar migration take?

The load itself is quick once the file is mapped; the timeline is set almost entirely by abstraction. A portfolio abstracted by hand or through a managed engagement runs on the abstractor's schedule, often weeks for a large batch. The same portfolio abstracted with AI, reviewed against the source, and exported to the CoStar template compresses the front end to minutes per lease, which is why teams increasingly abstract first and load in one pass. Whichever route you take, validate a sample after the import so the schedules CoStar produces are trusted from day one. For the full field checklist, see the commercial lease abstract template.