Short Court currently has the 20% off voucher at the top of this page for your first order, which is the lead deal and is best if this is your first purchase and you want the biggest single code discount. The extra 10% off sitewide is the other code available, and the sale shows items reduced by up to 25% with no code required. Both codes state they cannot be used in conjunction with any other offers.
If this is your first order and your cart is small (for example $50), use the 20% off voucher at the top of this page. On a $50 order, the 20% off voucher takes 20% off (percent 20%), leaving $40, so you save $10. The extra 10% code would take $5 off and leave $45, so the 20% voucher saves you more on this spend.
If this is your first order and your cart is larger (for example $200), the 20% off voucher still gives the biggest code saving. On a $200 order, the 20% off voucher takes 20% off (percent 20%), leaving $160, so you save $40. The extra 10% code would leave $180, a $20 saving, so the 20% voucher is better for first time buyers at this level.
If you are not a first time buyer and you cannot use the first order voucher, use the extra 10% off sitewide code. On a $200 order, the extra 10% code takes 10% off (percent 10%), leaving $180, so you save $20.
If you are buying marked down sale items the sale prices are already shown on product pages and no code is required. Sale items are reduced by up to 25% as shown, so a sale item originally priced $80 marked down by 25% would be $60, a $20 saving. Because both voucher codes state they cannot be used in conjunction with any other offers, treat the sale price as the price you pay unless the website explicitly allows a code to apply to sale items.
If you were hoping to stack discounts or combine codes remember both voucher codes say they cannot be used in conjunction with any other offers, so you cannot enter a second code at checkout. There is no separate newsletter or subscribe offer on this list to consider.
When choosing between these options, take whichever leaves the lower total for the same items. For first orders, the 20% off voucher at the top of this page beats the extra 10% code at every basket size in the examples above. For repeat orders or when the first order voucher does not apply, use the extra 10% code unless the items you want are already on sale at a greater percentage off; in that case buy at the sale price shown.