The district authority are responsible for making payments to the Parish Council, as part of the precept setting process. How they collect over 10 or 12 months doesn't affect the amount they must provide, by law, to the Parish or Police or Fire Authorities.
The district will have discounted an amount for bad debt already - You will have seen this on your precept information planning sheet (which documents how many houses there are in each, and relevant discount rates), which enable the parish to calculate the correct precept amount.