SECTIONSShield Platform Encryption
Tax Reporting supports Salesforce's Shield Platform Encryption on all current standard fields, and also supports encryption of files and attachments.
When encryption is enabled for a field, disabling the encryption later does not remove the querying restrictions on that field. This means that any current or future packages on your org which use that field must continue to support encryption on it. For example, when searching for accounts, users cannot filter by a field that is, or was, encrypted because the querying restrictions imposed by encryption don't allow filtering on encrypted fields.
Refer to the Salesforce Shield Platform Encryption Implementation Guide if you are considering enabling encryption on your organization. If you are unsure whether to proceed, contact your Salesforce representative before making any decisions.