This depends on the online casino you are playing. In general this starts from a (first) deposit of $1000.
High Roller Bonus Guide
A particular type of bonus that is attractive in the world of online casinos is the high roller bonus, which is also known as the VIP bonus.
Many online casinos offer what are called VIP programs where 'high rollers' are entitled to certain benefits. In a lot of cases, each online casino has different tiers available that rank all of their high rollers, from 'bronze, silver, gold and platinum' level.
Depending on how big the online casino is, the benefits that are available to high rollers and VIP players can include corporate invites to certain sporting events, though this is only really at the most popular global brands.
If an online casino offers a VIP program, you will often find that there are certain steps that you need to take in order to become a high roller, such as depositing more than you would for another bonus, playing regularly and making big deposits on a regular basis. As a result of this, because you are then regarded as a special customer, you are rewarded in kind.
The most common benefits of a high roller bonus is that you will get free spins on a regular basis, exclusive access to table games tournaments or high stakes poker tournaments, your own dedicated account manager in sometimes even merchandise.
Every online casino differs in its VIP program and if it is very new, you might find that it does not even have one. Compared to normal welcome bonuses, a VIP bonus usually requires you to deposit a lot more when you sign up to the site in order to get a high roller bonus.