Each employer's contribution report, together with any prescribed copies and supporting data, shall be filled out in accordance with the instructions and regulations applicable thereto. The prescribed forms may be obtained from or accessed by contacting the Board. An employer will not be excused from making a contribution report for the reason that no form has been furnished to such employer. Application should be made to the Board for the prescribed forms in ample time to have the contribution report prepared, verified, and filed with the Board on or before the due date. Contribution reports that have not been so prepared will not be accepted and shall not be considered filed for purposes of § 345.115 of this part. In case the prescribed form has not been obtained, a statement made by the employer disclosing the period covered and the amount of compensation with respect to which the contribution is required may be accepted as a tentative contribution report if accompanied by the amount of contribution due. If filed within the prescribed time, the statements so made will relieve the employer from liability for any penalty imposed under this part for the delinquent filing of the contribution report provided that the failure to file a contribution report on the prescribed form was due to reasonable cause and not due to willful neglect, and provided further, that within 30 days after receipt of the tentative report, such tentative report is supplemented by a contribution report made on the proper form.