Medicare Claims Processing Manual (Pub. 100-04), Ch. 23 § 40.4
Gap-Filled Fees Submitted to CMS by A/B MACs (B)
40.4 - Gap-Filled Fees Submitted to CMS by A/B MACs (B)
(Rev. 1, 10-01-03)
AB-01-162, AB-02-163
In accordance with §531(b) of the Benefits Improvement and Protection Act of 2000 (BIPA), CMS solicits
public comments on determining payment amounts for new laboratory tests. The CMS hosts an annual
public meeting to allow parties the opportunity to provide input to the payment determination process. The
CMS employs one of two approaches to establishing payment amounts for new laboratory test codes,
crosswalking and gap-filling. After considering public input regarding the new test codes, CMS determines
which approach is most appropriate for each new test code.
If the new test is comparable to an existing test, the new test is “crosswalked” to the existing test, and it is
assigned the local fee for the existing test and the corresponding NLA. The new test code and payment
amounts are included in the updated laboratory fee schedule annually.
If CMS determines that the laboratory fee schedule includes no sufficiently comparable test to permit
crosswalking, CMS instructs A/B MACs (B) to “gap-fill” the payment amount for the new test code. Gap-
filling is an empirical process of determining a payment amount in a locality using available information
sources. Usually the period during which gap-filled payment amounts are instructed is the year following
the introduction of a new code. During this period, A/B MACs (B) establish and use these payment
amounts; they may be revised in the course of the year. Also during this period, A/B MACs (B) must report
the gap-fill amounts to their ROs which are then forwarded to CMS CO. The CMS considers the gap-fill
amounts and uses them to establish the fees for the new test code in the next update of the laboratory fee
schedule.
In determining gap-fill amounts, the sources of information A/B MACs (B) should examine, if available,
include: charges for the test and routine discounts to charges; resources required to perform the test;
payment amounts determined by other payers; and charges, payment amounts, and resources required for
other tests that may be comparable or otherwise relevant. A/B MACs (B) may consider other sources of
information as appropriate, including clinical studies and information provided by clinicians practicing in
the area, manufacturers, or other interested parties. To assist each A/B MAC (B) in establishing a gap-fill
amount, A/B MACs (B)’ Medical Directors may meet and share information regarding the new test, though
without reaching a formal consensus.
Establishing payment amounts for new laboratory tests is inherently difficult, precisely because these tests
are new and as a result the types and extent of information available about them may be limited. Because
the circumstances of different tests may vary significantly, specifying in detail a method of using the various
information sources outlined above does not appear appropriate at this time. However, CMS designates a
new test code for gap-filling in instances where no test code seems sufficiently similar to make a crosswalk
approach appropriate. Accordingly, A/B MACs (B) should not determine a gap-fill amount by crosswalking
to the payment amount for another test code.
After determining a gap-fill amount, an A/B MAC (B) may consider if a least costly alternative to a new test
exists. If an A/B MAC (B) determines a least costly alternative test exists, the A/B MAC (B) may adopt the
payment amount of the least costly alternative test as the gap-fill amount for the new test code. The least
costly alternative amount will be considered the local fee, and CMS will use this payment amount in
establishing the NLA. However in this case, the A/B MAC (B) must report two payment amounts, the gap-
fill amount prior to determination of a least costly alternative and the payment amount that the A/B MAC
(B) has determined to be the least costly alternative.
A/B MACs (B) should also communicate the gap-fill amounts to corresponding A/B MACs (A) and (HHH).
A/B MACs (B) can seek assistance from RO staff to facilitate communication of the gap-fill amounts to A/B
MACs (A) and (HHH). The list of codes which A/B MACs (B) are required to gap-fill each year are
communicated in the annual instructions.
A/B MACs (B) provide their RO with gap-fill fees according to the date communicated by CMS (usually
May), to be used by CMS-Central for the development of subsequent or later laboratory fee schedules. A/B
MACs (B) submit the gap-fill fees in a right-justified format. These gap-fill data should be transmitted in an
ASCII file with the following file specifications to MStevenson@cms.hhs.gov with a copy to
Agreenberg@cms.hhs.gov to assist with coordinated collection of the gap-fill fees.
Data Set Name: CLXXXXX.TXT* (ASCII File)
(*Denotes A/B MAC (B) 5 - digit number)
Gap-filled Fees Record Layout
Data Element Name
Picture
Location
Comment
Year
X(4)
1 - 4
Set to Year (e.g., 2003)
HCPCS Code
X(5)
5 - 9
Modifier
X(2)
10 - 11
A/B MAC (B)
Number
X(5)
12 - 16
Locality
X(2)
17 - 18
00 = Denotes Single State
A/B MAC (B)
01 = North Dakota
02 = South Dakota
20 = Puerto Rico
40 = New Hampshire
50 = Vermont
Gap-fill Amount
9(5)V99
19 - 25
Prior to any determination of
a least costly alternative
Least Costly
Alternative Amount
9(5)V99
26-32
Least Costly
Alternative Code
X(5)
33-37