Tax Month End Date: The Tax Month End Date is set by the DIT. It always falls on 5th day of each month, which coincides with the DIT's Assessment Year calender. Please remember your CIS 300 Monthly Return must always bear a tax month end date of the 5th day of the following month, regardless of what actual monthly payment period you choose for paying the Sub-Contractor. What is the CIS tax month end date? CIS tax months run from the 6th of one month to the 5th of the next month. The 1st CIS tax month runs from 6th April 2008  to 5th May  2008  The 2nd CIS tax month runs from 6th May 2008 to 5th June 2008 The 3rd CIS tax month runs from 6th June 2008 to 5th July 2008, and so on. The tax month end date for a particular month always falls on the 5th day of the following month. The tax month end date for April will be 5th May 2008,  2008-05-05 The tax month end date for May will be 5th June 2008,   2008-06-05 The tax month end date for June  will be 5th July 2008,  2008-07-05    and so on. How it Ref.? : The CIS Contractor and Sub-Contractor spreadsheets which you download from our website now ask you to enter the tax month end date as one of the required fields. When you go to upload the spreadsheet to our website you are asked to  select the 'Tax Month End date for this return' and then to browse and choose the appropriate spreadsheet file to upload. The tax month end date within the file you choose to upload is then read and validated by our program to ensure that it agrees with the 'Tax Month End date for this return' which you have selected. If the two dates match the file can be uploaded, if the two dates are different the file cannot be uploaded. i.e. if you select to upload the spreadsheet for 05 June 2008, but you actually browse and choose a spreadsheet which contains 05 May 2008 as the Tax Month End date, the upload will be rejected. Conclusion :  Tax Month End Date has been adopted  into our system to cross check which month's data you want to eFile to the DIT. This  will  prevent you from eFiling the wrong  month's  data to the DIT.   Please remember your CIS 300 Monthly Return must always bear  a tax  month end date of the 5th day of the following month, regardless of what actual monthly payment period you choose for paying the Sub-Contractor.