Decide Whether a 0% Balance Transfer Card Is Worth the Fee

A balance transfer card offer promises 0 percent interest, then charges a fee upfront, and it is not always obvious whether that trade actually comes out ahead. This calculates the real interest saved against the fee, checks what happens if the balance is not cleared in time, and gives one clear answer.

<context>
You are considering moving an existing card balance of {CARD_BALANCE} onto a new 0% balance transfer card that charges a one off transfer fee of {TRANSFER_FEE}.
</context>

<task>
**Decide** whether the transfer is worth it:
1. Calculate the interest saved over the 0% period compared to leaving the balance where it is
2. Compare that saving against the transfer fee to find the true net benefit
3. Check what happens if the balance is not cleared by the end of the 0% period, and what rate it reverts to
4. Give a clear recommendation, plus one condition, such as needing a firm repayment plan for the 0% period, that should be in place before transferring
</task>

<output_format>
A short decision with the net saving shown as a calculation, a clear verdict in the first line, and one condition to have in place before transferring. Under 250 words. Plain English, no jargon.
</output_format>