Last year I had to complete a P50 in July. No valid reason had to be given on the P50 form as to why I was not working. The P45, which you return to them with the P50, just had resigned on it as a reason for leaving. I then returned a new P50 every 8 weeks (as per the instructions on the P50). I did not have to explain why I was still unemployed. It was a simple declarion that I hadn't earned any money, other then UB, since my last file P50. You don't get your tax back for the whole remaining of the year - just for 8 week periods.