Costa add compulsory tips to your account 6 euros per person per day for less than 8 day cruises and 4.50 per person perday for longer cruises. These may not be removed. Plus they add 15 percent to all bar charges. Those figures are for European cruises I think it is different for other areas.
The Process: In Europe, 6 euros per person, per day are added automatically to each adult's onboard account. In the Caribbean, the amount is $8.50.
Kids Too? The standard amount for children is 3 euros per day in Europe or $4.50 in the Caribbean.
Extra Charges: An automatic 15 percent gratuity is added to all bar bills. Gratuities in the spa are at the passenger's discretion, but 15 percent is the recommended amount.
They put 6 euros per day per person on your bill, which is shared by all their staff and is tremendous value, given the wonderful service that is offered.This way you need do nothing but you can always add a discretionary extra tip to anyone that you believe deserves it, although interestingly Costa does not encourage this practice and in fact their brochure states "please note that extra tips to the staff are not allowed".