ELCA congregations are not required to file IRS Form 990. IRS Publication 1828 explains this on page 22:
Exceptions to file Form 990, 990-EZ and 990-N
The following is a list of some of the organizations that are not required to file Form 990, 990EZ or 990-N:
See the form instructions for a list of other organizations that are not required to file. Some congregations that have unrelated business income must file a IRS Form 990 T to report unrelated business income tax (UBIT).