Enter a code in the Promo code box at checkout and tap Apply. You'll see exactly what it takes off before you place the order — checking a code never uses it up, so a typo or a change of mind costs you nothing.
Some codes take money off the items, some cover delivery, and some add credit to your account. A credit code is redeemed from your account rather than at checkout, and the credit can be spent anywhere on Kosmos.
A code can never be worth more than the thing it's discounting. Most codes work once per person, and some have an end date or a limited number of uses — if one has run out or expired, we'll tell you which.