How to Audit ILS Spend Across an Apartment and Multifamily Portfolio: A 30-Day Checklist

When to run an ILS audit, and what each trigger changes

Run it yearly and after any of these events; the trigger decides where you start.

CoStar, which owns Apartments.com, says its services are typically distributed to clients under "subscription-based license agreements that typically renew automatically, a majority of which have a term of at least one year", and that "upon renewal, many of the subscription contract rates may change" (CoStar Group 10-K, FY2025). Zumper's premium listings, by contrast, are month to month and cancelled by emailing Zumper "before the start of your next billing cycle" or from account settings (Zumper). Brynson works with Apartments.com, Zillow, Apartment List and Zumper as partners.

The 30-day ILS audit checklist, day by day

One owner runs it, with accounting on week 2 and regional managers on week 4. Use six months or more of data.

Time needed: P30D

1. 1

   Days 1 to 3: collect contracts

   Request every ILS contract, amendment and insertion order for every property, from your files and from each ILS. Record missing ones as findings.

2. 2

   Days 4 to 7: build the register

   Create one row per property per ILS with package, add-ons, basis, price, term, notice date, contracting entity and owner. Highlight notice dates in the next 90 days.

3. 3

   Days 8 to 11: billed vs contracted

   Match every invoice line to a register row and a property you still manage. Log each variance as a credit request.

4. 4

   Days 12 to 15: reconcile pay-per-lease

   Match each billed lease to a PMS lease credited to that source with a move-in date. Dispute cancellations, renewals and transfers with records attached.

5. 5

   Days 16 to 20: cost per lease

   Calculate cost per lease for each property on each ILS, complete-invoice months only, and band it against that ILS's portfolio rate. Flag cells under 3 leases.

6. 6

   Days 21 to 25: listing spot check

   For every above-band cell, compare rent, mandatory fees, beds and baths, availability and amenities with the PMS. Send conflicts to be fixed at the source.

7. 7

   Days 26 to 28: decide

   Apply the decision table to every cell and give each action an owner and a date before the notice deadline.

8. 8

   Days 29 to 30: approve and log

   Get approval for package changes, log who asked, which ILS, which property and status, and set the monthly reconciliation and quarterly review cadence.

Week 1: build the contract and package register

One row per property per ILS. If a property is on four sites, it gets four rows.

Week 2: reconcile invoices, including every pay-per-lease charge

Two checks, in this order. First, billed vs contracted: does each invoice line match the package and price in the register, for a property you still manage? Second, for pay-per-lease sources, does each billed lease match a signed lease in your PMS, credited to that source, that was not cancelled? Apartment List sells its marketplace as "Only Pay for Leases" (Apartment List), and Zillow Group's annual report describes a rentals "Pay-Per-Lease" product (Zillow Group 10-K, FY2025), so for many portfolios this is the larger check.

Keep both out of the performance analysis: a billing variance means the invoice is wrong, not the ILS. Read your contract's credit terms first.

Nine places ILS money leaks, and the test for each

These are the findings a first audit usually produces. Each comes with a test you can run on the register, the invoices or the PMS.

1. 01

   Auto-renewal at an old or higher rate

   A subscription renews because no one sent notice. Test: list every row with a notice date in the next 90 days and a named owner who will act on it.

2. 02

   A package change that never reached the invoice

   A downgrade agreed by email keeps billing at the old price. Test: for every change in the last 12 months, does the next invoice show the new price?

3. 03

   Pay-per-lease charges for cancelled leases

   An application cancelled before move-in can still be billed. Test: match every billed lease to a PMS lease with a move-in date, then read your contract's definition of a billable lease.

4. 04

   Pay-per-lease charges for renewals and transfers

   A current resident who views a listing, then renews or transfers, is not a new lease from that source. Test: check billed names against current residents and dispute under your contract's lease definition.

5. 05

   Sold or transferred properties still on the invoice

   Multi-property invoices hide one extra line. Test: compare invoice property lines with your current managed-property list each month.

6. 06

   Unused add-ons

   Featured placement, extra photos or premium slots bought for lease-up stay on after stabilization. Test: list every add-on, why it was bought, and whether that still applies.

7. 07

   Per-listing plans sized for the wrong count

   Per-listing pricing, such as Zumper's tiers from $10 a listing for 5 listings to $4 a listing for 200 (Zumper), charges for slots, not leases. Test: compare listing slots paid for with units actually available.

8. 08

   Quarterly or annual billing read as monthly

   An invoice covering three months makes one month look expensive and two look free. Test: allocate every invoice to the months it covers before calculating cost per lease.

9. 09

   Paying for exposure on a listing that misstates the property

   A wrong rent or a missing mandatory fee costs leads, and an advertised fee that does not match what you charge is a fee-disclosure problem too (see rental junk fee laws by state). Test: the five-field check in week 4 on every above-band cell.

Week 3: cost per lease by property against the portfolio rate

Divide each property's spend on each ILS by the PMS leases credited to that ILS over the same complete-invoice months. Compare the result with that ILS's portfolio rate, not with other ILSs. The ranking can reverse from one property to the next; see the best ILS for multifamily. The full method is in cost per lease by source.

• Band each cell: below the portfolio rate, within 15%, or above it.
• Flag small samples: a cell built on fewer than 3 leases is low confidence. Widen the window before acting on it.
• Put billing models on one basis: add platform fees to pay-per-lease charges and add-ons to subscriptions. See ILS pricing models.

Week 4: spot check listings before you blame the channel

Across 6,000 properties and 1.6 million units, Brynson found that, at origination, nearly 89% of communities described themselves differently across listing sites. 97% of those listings had been updated within the previous 90 days, yet conflicting mandatory fees, missing amenities and contradictory terms persisted (listing accuracy report). "Recently updated" does not mean accurate.

For every above-band cell, compare five fields with the PMS: starting rent, mandatory fees, beds and baths, available units, and headline amenities. An above-band cell on a listing with conflicts is a data problem first: fix it at the source and re-measure. The full field checklist is in the ILS listing audit.

Turning findings into package changes: cut, downgrade, hold or upgrade

Each property x ILS cell gets one action and one owner.

"At stake" is the gap between a cell and its portfolio rate: a reason to look, not savings. Nothing is saved until a package changes and the leases hold.

Reducing ILS dependency without losing leases

Test a downgrade at a few properties before you cut across the portfolio.

1. Pick two to four above-band properties with clean listings and enough traffic to measure.
2. Downgrade one tier rather than cancel, and change nothing else there during the test.
3. Agree the restore rule first: for example, restore if leads, tours and leases all fall over 60 to 90 days.
4. Track leads, tours and signed leases by source from the PMS, not the ILS dashboard.
5. Roll out only what held, property by property, timed to each notice date.

Frequently asked questions