You can correct the mailing date on the printed postage by selecting the corrected date and creating a postage label with zero value. You can then stick this to the left of your previous postage label. You must not overlap the labels.
To print a date correction:

1. From the home screen click the send a letter tab.
2. Click on your chosen print media. Please note you are unable to print a zero value print on an Envelope.
3. On the right hand side of the print screen click Date correction with zero value print.
4. Select the correct date from the calendar.
5. Choose your printer if you have more than one installed and ready.
6. Click Print.

Printing a date correction only prints a new date. You will not be charged for postage. You can print only one zero value postage at a time.