The Regulations pertaining to Assessment Area delineation proscribe "substantial" encroachment over MSA boundaries. However, when MSA's or non-MSA geographies are within the same CSA you may cross the MSA boundaries and maintain one AA as long as the area is contiguous.
When examiners evaluate your CRA performance they will breakout AA's constructed in this way into the MSA's that constitute part of the AA as long as you have at least one deposit-taking facility in each MSA. If you simply have branches in only 1 MSA then they will evaluate the AA as the combination of AA's.
The new (2013) Q&A did not change anything with respect to this topic.
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