Internal Revenue Manual
11.5.2.2.5 (10-18-2018)
Congressional Inquiries
Congressional inquiries, whether by letter, fax, e-mail or telephone call, will be assigned and worked depending on the following criteria:
Tax account related congressional inquiries will be assigned to the LTA [Local Taxpayer Advocate] Office (for example, an inquiry from a constituent where the IRS denied an Earned Income Tax Credit (EITC) claim).
Non-tax account related congressional inquiries will be assigned to the Local DL [District Liaison] (for example, an inquiry from a constituent wanting to know how to claim the EITC).
. . .For all correspondence that will be worked locally by the DL, an acknowledgement should be sent to the congressional office within two business days of receipt. Timing of a final response may depend on support from other IRS components. When a final response is delayed, interim responses should be sent every two weeks, unless the congressional office agrees that less frequent updates are appropriate. All congressional inquiries should be resolved within 20 days of receipt, unless support from another IRS component prevents it.
IRM 1.10.1 provides a general guide for formatting written correspondence. See also IRM 11.3.4, Disclosure of Official Information - Congressional Inquiries.
Any congressional correspondence received that could have nationwide implications should be brought to the attention of the DCL [District Congressional Liaison] Branch Chief.
DLs should document all written responses to congressional inquiries per instruction in IRM 11.5.2.1.4, Program Controls.

11.5.2.1.4 (10-18-2018)
Program Controls
CAP Contacts Database: This database is used by DLs to record inquiries from congressional offices. DLs are required to record all significant inquiries. For purposes of this paragraph, significant inquiries are those that require more than 5 minutes to resolve. However, DLs are encouraged to record all inquiries. The data collected by this database is used by the Chief, DCL Branch to provide leadership with monthly trend analyses and quarterly business performance results (BPR). Instructions for DLs and other database users are available on the DCL branch SharePoint site.
Outlook Tasks: An Outlook Task will be created for each congressional inquiry that cannot be immediately resolved. The CAP Contacts Database offers a convenient option to create a task while recording a new contact in the database. Information from the new contact will be automatically copied to the task.

I should probably mention here that my son once worked on a Senator’s local staff and is familiar with how this system works in practice.

11.5.2.2.3 (10-18-2018)
Congressional Office Visits
It is important that the DL and LTA coordinate regular local congressional visits. The purposes of these visits are to:
Develop and maintain relationships and reinforce communications channels.
Discuss corporate messages and topics of mutual interest.

Planning the Visits
The DL and LTA should identify trends and subjects for discussion. Review recent congressional correspondence from Members to identify issues so the DL and LTA can be prepared for possible discussion.
Check with the operating/functional divisions to identify current national and local issues or items of interest. Working with Stakeholder Relationship Management Local Councils is one way to identify operating/functional divisions issues (i.e., small business workshops, changes in procedures, Taxpayer Assistance Center hours and services, VITA, etc.).
Develop a specific agenda and/or outline, tailored to individual offices or Members, if necessary.
Prepare handouts and/or information packets (i.e., press releases, VITA site listings, contact numbers for constituents, announcements of special IRS events, etc.).
Scheduling Visits
Make contact with congressional staff to schedule the visits at least one month in advance
Suggest a date and time for the visit and ask for an appointment. Typically, 30-60 minutes should be sufficient. Also discuss a tentative agenda and ask if there are any concerns that they would like addressed. Be flexible with scheduling visits because the chosen dates and times may not work for the congressional staff.
To confirm the appointment, send each staff member an e-mail or letter with date, time and topics.