Cancel an annual plan early: what is left unused, what you get back, and what cancelling really stops.
Arithmetic only — not tax, accounting, legal or investment advice. Check against current rules.
Cancel mid-term cost: Unused value is the price paid over the term, times the months left. It is refunded only when the contract says so; otherwise cancelling stops the renewal, not the bill already paid.
Quoted from the toolbelt spec, the document this tool was built against.
Negatives are parenthesized because that’s what a statement does. The rest is four promises.
Amounts are integers in the currency's smallest unit, end to end. A float never touches a cent.
Rounded once, at the end. Rounding each operand is how a split stops summing to the whole.
The arithmetic lives in one unit-tested module, and the extension uses the same one.
There is no request to make. What you type stays in this tab and is gone when you close it.
A calculator answers the question once. These carry the answer into a product, name what it computed, and argue the method.
Worked example. Type over it.
Result
The same 5 months on the monthly plan would have cost 625.00: 575.00 less than you net-paid.
With no refund, cancelling now stops the renewal, not this year's bill. The months already paid for are spent either way.