Hi Sarah,

Thanks for posting in the Community! 

Thank you for reporting the unexpected behavior you've encountered when recording GST payments. There is a reported Product Investigation under INV-109291 for Unable to record GST payment with the correct date.

I recommend contacting our Customer Care Team. That way, they can add your company file to the list and you can get an updated notification once a fix has been deployed. 

Post again in the Community if you have other questions.