The payback points you earn during a month are counted every month. There is a cut off point which is the last day of the month, at midnight. Any payback points earned after this date will be counted in next month's statement.
Points statements for the month are issued on or around the 20th of the month, telling you what you have earned in the previous month. The total you have earned so far for the current payback period is available to view in your My Payback page.
The final count is made after the end of each of the 6 monthly payback periods. There are therefore two final counts each year, one on or around the 1st of June and the other on or around the 1st of December.