P11d software for accountants

Can anyone recommend software that will manage and process P11d across a client portfolio.

I'm not looking for something "stand alone" for each client or anthing that adds onto a clients payroll.

I need something like tax return software that will enable me to track progress, write to clients with details of previous data, have car details etc etc. We currently have a few hundred clients that we complete P11ds for and it can be a major issue making sure that none are missed, the correct questions asked etc.

Thanks