We’re updating mandate identifiers to use Mollie’s longer API identifier format. This follows the earlier update to API identifiers and brings mandates in line with the same standard.
What's evolving?
Legacy mandate identifiers contain 10 characters after the mdt_ prefix. Newly created mandates will use a longer identifier, with up to 22 characters after the prefix. The mdt_ prefix stays the same.
This change applies to newly created mandates, including mandates created automatically through a payment. Existing mandates keep their current identifiers and remain usable. You do not need to recreate them or ask customers to authorise them again because of this update.
What does this mean for you?
If you maintain a custom integration, review any systems that store, validate, or pass mandate identifiers - including subscription platforms, billing software, and other connected systems:
- Database storage: Allow at least 40 characters for the complete identifier, including its prefix.
- Custom validation: Remove checks that require exactly 10 characters after mdt_. If you validate the format, check the expected prefix without enforcing a fixed length for the remainder.
- Handling identifiers: Store and send the complete identifier exactly as returned by Mollie. Treat it as a string; you do not need to decode or interpret it.
- Compatibility: Make sure your integration accepts both existing shorter identifiers and new longer identifiers.
These storage and validation recommendations follow our existing identifier migration guidance. You can also consult the API identifier documentation.
If you use a plugin or an integration maintained by another provider, check with that provider that it supports longer mandate identifiers.
The identifier change does not alter how you use mandates for recurring payments. However, truncating or rejecting a longer identifier could prevent your integration from retrieving a mandate or using it in a payment request. If you encounter an issue, check that the full identifier is preserved throughout your integration and contact Mollie Support with the relevant API error and mandate identifier.