Nil returns must be reported either monthly or quarterly depending on the size of the payroll as set out by HMRC.
http://www.hmrc.gov.uk/payinghmrc/paye-nil.htm
The reporting links are:
Quarterly
http://www.hmrc.gov.uk/tools/payinghmrc/no-quarter-payment.htm
Monthly
http://www.hmrc.gov.uk/tools/payinghmrc/no-monthly-payment.htm