Overview
Consumers can make changes to their plan at any time. Whenever a change is made to an active subscription plan during a billing period, the DVM automatically calculates a Pro-rated Charge or Pro-rated Refund based on how many days remain in the current billing cycle. This ensures consumers only pay for what they use, and receive fair refunds for what they don’t. Here are the changes which can be made to an active subscription offer which will result in a Pro-rated Charge or Refund calculation:Upgrade
Consumer moves to a higher-priced Product tier.They are charged the price difference for the remaining days in the period.
Downgrade
Consumer moves to a lower-priced Product tier.They receive a refund of the price difference for the remaining days, starting the day after the change.
Immediate Cancellation
Consumer cancels their subscription immediately.They receive a full refund for the remaining days, starting the day after cancellation.
How time is calculated
The DVM works in whole days. Partial days are always rounded up to the nearest full day — The DVM never issues a charge or refund for fractions of a day.DVM billing uses ISO timestamps internally for precision, but all pro-ration amounts are computed at day-level granularity using
ROUNDUP(duration / 1 day) before the proration factor is applied.The pro-ration formula
Every pro-rated amount is calculated using the same core formula:Variables
Scenario details
⬆️ Upgrade — pro-rated charge
⬆️ Upgrade — pro-rated charge
When a consumer upgrades to a higher tier, they are charged the price difference (ΔP) for the days remaining in the cycle, inclusive of the change day itself.Example — Upgrade on Day 13 of a 31-day cycle (ΔP = £50)
⬇️ Downgrade — pro-rated refund
⬇️ Downgrade — pro-rated refund
When a consumer downgrades to a lower tier, they receive a refund of the price difference (ΔP) for the remaining days in the cycle.The change day itself is not refunded — the refund starts from the following day.Example — Downgrade on Day 18 of a 31-day cycle (ΔP = £50)
The refund starts from the day after the downgrade. The consumer is not refunded for the change day itself — they are charged for that day at the higher tier price, regardless of when the downgrade occurs during the day. This applies even if the consumer upgraded and downgraded on the same day.
❌ Immediate Cancellation — pro-rated refund
❌ Immediate Cancellation — pro-rated refund
When a consumer immediately cancels their subscription, they receive a refund of the full renewal price (P) for the remaining days in the cycle.The cancellation day itself is not refunded — the refund starts from the following day.Example — Cancellation on Day 17 of a 31-day cycle (P = £50)
The refund starts from the day after cancellation. The consumer is not refunded for the cancellation day itself — they are charged for that day at the full subscription price, regardless of when during the day the cancellation occurs.
Quick reference
Use this as a mental model: the later in a cycle a change happens, the smaller the pro-rated amount — because fewer days remain.Same-day upgrade and downgrade
If a consumer upgrades and then downgrades on the same day, both pro-ration calculations apply independently and are issued as separate transactions.
Because the downgrade refund is calculated from the following day, the consumer is always charged for the day on which they held the higher tier — even if they downgraded later the same day. This prevents consumers from accessing premium features at no cost by upgrading and immediately downgrading within the same day.
Example — Upgrade then downgrade on Day 15 of a 31-day cycle (ΔP = £5.00)