The key point first: IOSS only helps with the printed planners, not the digital templates. The Import One Stop Shop covers distance sales of goods (not services) up to €150 to EU consumers. With IOSS, you charge the customer's own country's VAT rate at checkout and report it through one EU IOSS registration in a monthly return — your customers then get their parcels with no extra VAT or clearance charges on delivery, which is a real conversion boost.
For your digital templates, IOSS doesn't apply at all: B2C digital services to EU consumers go through the non-Union OSS instead, which is a separate quarterly scheme. There's one catch for a UK seller: you can't register for IOSS directly — you need an EU-established intermediary to register and file on your behalf, which comes with a fee, so it only pays off once EU goods volumes justify it.
If you don't use IOSS, the alternative is selling Delivered Duty Unpaid (DDU): the customer pays EU import VAT and any carrier handling fee when the parcel arrives, which you need to warn them about clearly at checkout to avoid complaints. Another realistic route for a small seller is selling via an online marketplace, where the marketplace itself handles the VAT. Keep the two product types apart in your bookkeeping — services vs goods at €150 or under — because each has its own scheme and its own return.
