Thank you for the question.
Your credit record is made up of various aspects and is built around your payment history. Your payment history reflects everything that happened on an account on a month to month basis for the last 24 months.
If you fall into arrears the flag will indicate such. 30 day, 60 day 90 days arrears etc will be reflected on the specific account and on the specific month that it fell into arrears. Each type of flag contributes positively or negatively to your credit score.
Paying short will reflect on your payment history and will definitely affect your credit record. Paying only half of the instalment is much better than a total default however.
I would suggest that you communicate with your credit providers and give them a heads up that payment will be short this month. Make an arrangement with them in writing. In many cases they will update your credit record as full payment received.
It is important to manage your credit and credit providers wisely if you are to maintain a good credit record.