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Filing Instructions


General Information

Tax preparers filing on behalf of multiple clients may register as a Third Party Bulk Filer (TPBF). A registered TPBF has the ability to “key and send” or “upload” all their clients’ returns at once completing the upload process by creating a dynamically defined file for the particular return they are filing.

If you “key in” the information, you will see the TSC uses the same type of process that individual taxpayers use when they submit their filing. To “upload” a file, you will first prepare a file with your clients' information. Each row of your data will represent a different record. You may dynamically arrange these fields in any order. Additional fields, containing information for your own particular use, must be identified as "filler fields." We will disregard these columns in the upload process.

We will then review your file for errors and accept all returns without errors. Accepted returns will receive a unique confirmation number that will act as your "proof of acceptance." If a return has errors, we will provide you with a list of the failed records and an explanation of the problem. You may correct your file and resubmit the failed records.

Amended Returns. The following taxes can be amended electronically. If you discover an error with a particular return, you must correct it using the Key and Send – Single Client Filing option. This is true even if the incorrect return was originally uploaded.

  • Form OS-114, Sales and Use Tax Return
  • Form OP-210, Room Occupancy Tax Return
  • Form O-372, Admissions and Dues Tax Return
  • Form OP-336, Nursing Home User Fee Tax Return
  • Form CT-941, Quarterly Reconciliation of Withholding
  • Form CT-945, Annual Reconciliation of Withholding for Non-Payroll

Bulk Filing Options. Click on any the links below to learn more about each electronic filing process.