Allow bills to have introductory rates

Support guidelines

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[x] My request is not listed as a very good idea, but unfortunately...
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Description

I would like Firefly to be able to create bills which might have an introductory rate. For example, the first 6 months of an 18 month contract might be half price.

Service providers often offer introductory rates (e.g. £x.xx for the first a months, then £y.yy for the next b months). It would be great if you could setup a bill to take this kind of dual-rate into consideration. I appreciate that there needs to be a line drawn with how flexible the Bills feature is, but (certainly in the UK) this specific approach is quite common.

Solution

In the Bills feature, allow the user to set the Bill value to a specific amount for the first X months, and then another value for the subsequent months.

What are alternatives?

No response

Additional context

I appreciate that the Min and Max amounts go part way to achieving this, but for bills of known value (such as TV/internet/cable etc) this feature would be useful.

firefly-iii / firefly-iii