What is the credit consumption order in Valid Email Checker?

Every time Valid Email Checker deducts credits — a single verification, a bulk upload row, a public-API call — it walks your credit buckets in a fixed priority order and pulls from the highest-priority bucket that has a balance. The order matters because the buckets have different expiration rules.

The order, in plain English

1. Monthly bucket first. Subscription credits drain here until the bucket hits zero.
2. Legacy "rollover" bucket second (only present on accounts that pre-date the policy change). These were carried-over subscription credits from a previous policy. New accounts will not see this bucket — see the legacy rollover bucket.
3. Pay-As-You-Go bucket last. PAYG credits never expire, so VEC drains them last to preserve your never-expire balance for as long as possible.

How a single deduction works

When you verify a single email, the system locks all three buckets for the duration of the operation, deducts one credit from the highest-priority bucket that has at least one credit, updates the totals, and logs a row in your Credits History showing which bucket the credit came from. The whole sequence is atomic, which means it either fully succeeds or it rolls back. There is no partial-state where one bucket got decremented and another did not.

How bulk and API deductions work

A 10,000-email bulk verification is not 10,000 separate decisions. The system computes the total cost (10,000 credits), then drains buckets in priority order to cover it. So if you had 3,000 Monthly and 9,000 PAYG, the deduction would take all 3,000 from Monthly and 7,000 from PAYG in one transaction. The Credits History will show two rows for that job — one per bucket touched — so you can see exactly where each credit came from. See how monthly credits get used first for the reasoning.

Unknown auto-refund happens against the same bucket it was taken from

If a verification returns Unknown, VEC automatically refunds the credit to the bucket that originally paid for it. A Monthly credit that became an Unknown refund returns to Monthly. A PAYG credit returns to PAYG. The refund shows up as a refund row in Credits History tagged with the matching bucket.