e-filed amended

@freeder Direct your client to the IRS' payment portal to make the payment electronically.  Any reason your client would rather send in a paper check?  If you search the forum, there is no lack of questions about checks not having been processed by the IRS and those clients' accounts showing outstanding balances due as a result.  In time, these will get resolved but it adds to the confusion and could unnecessarily distress your client.

Here's a link to the IRS webpage for payment: https://www.irs.gov/payments