Which ink does the Epson Expression Home XP-400 use?

The Epson Expression Home XP-400 uses Epson 200 and Epson 200XL.

No. The Epson Expression Home XP-400 is an inkjet, so it prints with liquid ink from a cartridge, not toner powder, and no toner cartridge fits it. If you were searching for Expression Home XP-400 toner, the part you want is Epson 200 and Epson 200XL.

Yes. Besides the standard cartridges it accepts Epson 200XL. A high-yield XL holds more ink and costs less per page, which is worth it if you print often.

Epson can stop third-party ink working here with a firmware update, and it is the update rather than the cartridge that does it. The least documented row on this page. Epson publishes no current guide or support page for the Expression Home XP-400 at all, so there is nothing model specific to read either way, and the status rests on what Epson says about its cartridge range as a whole. An older machine like this is unlikely to be sent new firmware, which cuts the practical risk without changing what Epson reserves the right to do.

Rated yields run from about 165 pages (Epson 200) to about 500 pages (Epson 200XL), depending on the cartridge. Real-world yield depends on how much you print and how much ink each page uses.

By list price the lowest cost per page here is the Epson 200XL at about 4.9 cents per page. A reliable compatible or remanufactured cartridge can lower that further.