Duration this calendar Year and next calendar Year

I need a solution for users who want pay for this calendar year (no problem) and/or for the next calendar year or for both. So i need a validity duration for next calendar year. How can i add a validity duration for next calendar year? Or is ther a better solution

thanks in advice

[mod note: thread moved]

.. no one can help?

You want to allow them to pay for this calendar year as well as optionally the next calendar year? To do this set your plans duration to this calendar year. Then set your plan to allow renewal in advance by 1 year. Then you can optionally renew after subscribing in advance by 1 year giving them 2 years of subscription.

thank you very, very much, i will try it