How can I check the reason why an end-customer was unable to make a payment?

Use the Transactions API. For v0, check the “Get a pending transaction” endpoint under data->reason. For v1, use the “Get a transaction” endpoint under data->decline_reason.

How are micro-deposits monitored?

Micro-deposits are monitored by Plaid, not Synctera. Plaid pushes two credits and a debit to the end-customer’s account. The end-customer confirms the deposits via the Plaid UI in the Synctera app.

Are there any differences in the Plaid linking process depending on the specific bank or credit union?

No, unless the bank/credit union is not supported by Plaid. In that case, Synctera will have to do the micro deposits verification.

Can the end-customer link multiple bank accounts via micro deposit account verification?

Yes, as long as it’s not the same bank account multiple times. Synctera has a configuration to prevent linking the same external account across customers, but this can be turned off upon request.