HM Revenue and Customs will pay a £75 tax-free bonus to small employers filing their 2008/09 Employer Annual Return online this year. Employers who have fewer than 50 employees on their books can file on paper or online, but only those filing a valid online return will qualify for the £75 reward. Employers with 50 or more employees must file online, or face a penalty. Agents, tax advisers and payroll bureaux can file on behalf of their clients - small employers will still qualify for the £75 tax-free payment. Unrepresented employers must register with HMRC's 'PAYE Online for Employers' service. It can take up to a week to receive the activation PIN after registering. Employer Annual Returns are due by 19 May, or late-filing penalties will be served. HMRC's Sue Williams said: 'We are accepting returns now, and would urge all employers to send them in as soon as they are ready, to avoid any last-minute rush.'