Below is an extract of this IRS document:
Existing Installment Agreements –For taxpayers under an existing Installment Agreement, payments due between April 1 and July 15, 2020 are suspended. Taxpayers who are currently unable to comply with the terms of an Installment Payment Agreement, including a Direct Debit Installment Agreement, may suspend payments during this period if they prefer. Furthermore, the IRS will not default any Installment Agreements during this period. By law, interest will continue to accrue on any unpaid balances.