- The return itself is not complete.
- Required schedules are either incomplete or missing.
- The tax identification number (FEIN/SSN) is either incomplete or is missing.
- Failure to notify the Office of Tax and Revenue when there is a change in the tax year or in the business address.
- Using the phrase "see attached" instead of completing the return. "See attached" is to be used only to indicate that additional information is being provided.
- Signatures of officer, title and/or corporate seal are missing from the return.
- Failure to include with the return full payment of the balance due.
- Requesting that the overpayment of tax from a prior year be credited as an estimated tax payment when a refund of the overpayment has already been issued.
- Failure to file a return when no tax is due. Filing a return in this situation will prevent a delinquency notice from being issued and other compliance actions.
- Tax payment is not made payable to the "DC Treasurer."
- Failure to make the full estimated tax payment.
- Failure to include the full payment of tax when filing an extension of time to file request. If the tax due when the return is filed is more than the payment included with the extension request, then penalties and interest may apply.
- Failure to complete the apportionment factor section or making an error in determining the factor.
- Failure to prorate the $5,000 exemption (line 33 of form D-30) when a D-30 is filed for a tax period of less than a full year.
- Failure to notify the Office of Tax and Revenue of adjustments made by the IRS to your federal return.
- Mailing multiple returns in the same envelope. (File one return per envelope)
- Making one check/money order to cover the tax liability for multiple returns. Please use a separate check/money order for each return. Enter your tax ID, the form being filed and the tax year on the payment.
- Using the incorrect return for the tax year.
- Failure to fill in the amended return oval on the form when filing an amended return.
