Answer by Ellery Leung:
Here are some of my ideas on your questions:
I am not fully understand your question, so here I put an example here to illustrate:
Assume that a customer subscribes for a Monthly service.
- Monthly plan: $10,
- Annually $100 ($20 Discount).
- This person subscribes for 4 months already (spend $40).
- How should I calculate the deduction from the price of higher plan? >> The without any discount or so on will be $60 ($100 – $40). However, you may want to thanks them by providing a special offer for people who spend 3 months or more on your service by offering $50 (instead of $60) for 8 months (Annual 12 months – 4 months usage) service. UI? I am not sure, maybe you can ask your web designer to think about it. Normally I will setup an autoresponder to people who spend x months on your service to offer $y discount.
- You can TEST. Again, if you want your customer to renew/restart using your services, offer something valuable to attract them to do so. It does not limit to price inducement. For example, if you offer SaaS service, you can give a book, or free 24 hours customer premium support, or additional months offer. We do not have crystal ball, you know only when you do a small test.
- Again you do a test. The suggestion is quite similar to #2 so I would rather not repeat here. Test it and you would know.
Hope it helps.