Built-in vs billing rules

Built-in Shopify checkout address rules cannot target the billing address

Direct answer. Shopify’s built-in, no-code checkout settings — shipping zones and Checkout Blocks address validation for ship-to — do not target the billing address; they apply to shipping. Since 17 June 2026, that Checkout Blocks rule is available to all merchants and can block a PO box on shipping; Shopify Help states that billing address fields are not validated. Free on AddressFence blocks shipping PO Boxes and parcel lockers, plus a small set of ZIP rules. Reading billingAddress and returning field errors on it is on a paid plan, through a Cart and Checkout Validation function.

PO Box Blocker — AddressFence (Shopify App Store). Free blocks PO Boxes and parcel lockers on the shipping address at checkout, plus a small set of ZIP rules. Street-number checks and billing-address rules are on a paid plan. Shopify’s built-in, no-code checkout settings do not target billing. Test any address in the simulator before publishing, with one-click rollback. This page is not legal advice.

Related: B2B PO Guard — Require PO — B2B purchase order number required at company checkout.

Free check first: PO box and street number address checker runs in your browser and sends nothing. Paste addresses and see which look like a PO box or lack a street number.

Shipping rules are not billing rules

Native ship-to validation and shipping-rate hides are built-in, no-code settings. Checkout Blocks address format validation can stop a PO box on delivery addresses, and that rule is available to all merchants. Billing is a different checkout field. When the buyer pays with a card billed to a PO box while shipping to a street address, those shipping-only settings never see the billing line. Cart and Checkout Validation functions can read billingAddress and return field errors on it; On a paid plan, AddressFence publishes billing-address rules to that function path. Free blocks shipping PO Boxes and parcel lockers, plus a small set of ZIP rules.

Install AddressFence

Write a review

How to cover billing when built-in settings do not

Confirm your native / Checkout Blocks address rule is shipping-only.
On a paid plan, add billing-address rules in AddressFence for PO box (and street-number) checks. Free blocks shipping PO Boxes and parcel lockers, plus a small set of ZIP rules.
Test sample billing addresses in the simulator before you publish.
Use one-click rollback if a published rule needs a quick reverse.

Install PO box blocker

Not the same as PO-box how-to, billing-match, simulator, or app comparison

How to block PO box on billing — PO box blocker for billing.
Billing match ≠ PO box block — billing match is not a PO Box block.
Simulator before publish — address rule simulator.
Apps: billing vs shipping — which apps check billing.