Mailchimp can point to a state; Klaviyo can only point to a rule

Mailchimp itself charges US sales tax in twenty-one jurisdictions — Colorado, New York, and Texas among them — calculated from the customer’s address, with exemption limited to nonprofits and government bodies that supply supporting documents; no per-state or local calculation is offered for the customer’s own sales. Klaviyo charges the same kind of tax, at state and local level from the billing address, but publishes no list of which states at all; its exemption clears within three to five days once a certificate is filed, and its own Terms place the tax burden on the customer without ever naming who carries the resulting nexus.

Neither vendor makes room for anything but a card, just for different amounts of money

Mailchimp accepts only card, PayPal, SEPA, or iDEAL under section eleven of its terms; invoicing, purchase orders, net-30, ACH, and a W-9 are all absent, and what the platform calls an “invoice” is really a relabeled receipt. Card stays the only method through Premium, at three hundred fifty dollars a month, and past two hundred thousand contacts pricing moves to a custom plan with no stated tier. Klaviyo at least opens a contracted path — ACH or wire, with a W-9 supplied automatically — but only above two thousand dollars a month of plans; below that line it is card only as well, billed in advance.

Mailchimp bars the very data a HIPAA buyer would bring

Mailchimp hosts on its own servers in the US, naming no region and no third-party host, and holds SOC 2 of an unspecified type plus ISO 27001 in its own name; FedRAMP, StateRAMP, GovCloud, and any HIPAA business associate agreement are all absent, and importing regulated sensitive data is prohibited outright by its own terms. Klaviyo names a location, AWS-East-1 in Northern Virginia, and a fuller set of its own certifications — SOC 2 Type II, ISO 27001, ISO 27017, PCI DSS — but reaches the same dead end: no HIPAA BAA at any tier, and a Data Processing Agreement that allows storage anywhere Klaviyo or its sub-processors maintain facilities.

Klaviyo ships nearly twice the languages, and still leaves more untranslated

Klaviyo ships eleven interface languages, splitting Spanish into a Spain and a Mexico variant while keeping English as a single entry; Flows AI, pre-built templates, and dynamic variables all stay outside the translation. Mailchimp ships six — English, Spanish, French, Portuguese, German, Italian — with video tutorials captioned in only five of those, Italian excluded, a translation layer distinct from the fifty-plus languages available for sent-content itself.

Leaving one for the other means rebuilding it by hand

Mailchimp’s own migration guide for Klaviyo customers is entirely manual: export by CSV, rebuild segments and automations by hand, copy HTML over one template at a time, and handle SMS contacts separately. Klaviyo, for its part, only accepts subscriber imports by CSV or Excel, unsubscribes routed to a suppression list, and event history through a strict CSV format — each file capped at fifty megabytes, with no bulk migration path from Mailchimp offered either way.

A named state list still doesn’t answer who owes what

Mailchimp’s twenty-one named jurisdictions give a merchant something to check against; Klaviyo’s unnamed list gives nothing to check at all. Neither difference changes the more basic fact that both vendors leave nexus determination for a merchant’s own downstream sales entirely on the merchant — naming a state you are taxed in is not the same as telling you where you owe tax yourself.