Screenshot by CNET

HBO Max, the HBO-centered streaming service that AT&T's WarnerMedia set to launch May 27, will offer a month-long free trial to most AT&T wireless and internet customers who don't qualify for a more generous promo. And other AT&T customers can qualify for a three-month or even a year-long free trial.

Earlier this year, HBO Max said that people who already subscribe to HBO via AT&T would get the upgrade to Max for no additional cost -- that meant HBO customers through DirecTV, U-verse, AT&T TV Now, AT&T TV and AT&T wireless users can add HBO with certain unlimited plans.

On Tuesday, AT&T specified which of its customers gets HBO Max included at no extra cost, who gets a one-month trial and who gets a three-month trial. The easiest way to figure out what you qualify for may be to check your account online or in the myAT&T app.

HBO Max is set to be one of the final entrants in the streaming wars, a seven-month window when media giants and tech titans are releasing a raft of new streaming services to take on Netflix. HBO Max was betting it could grab your interest by amping up HBO's existing streaming service with a sprawling catalog of hit shows and movies and a big-budget slate of exclusive originals packed with big-name stars.

HBO Max was set to cost $15 a month when it rolls out in the US May 27, unless you qualify for a promo.

The following is AT&T's breakdown of who among its customers qualifies for which deal:

Video customers:

HBO Max at no added cost: Access to HBO Max will be included in DirecTV Premier and Lo Maximo; U-Verse U400, U450, and U450 Latino; and AT&T TV Now Max packages, as well as a new AT&T TV Premiere package coming soon.

One year free: New AT&T TV Choice, Xtra or Ultimate, and Óptimo Más package customers and new DirecTV Choice, Xtra, Ultimate, Más Ultra or Óptimo Más package customers, will be eligible to receive HBO Max included for a year. Customers can sign up for these packages ahead of the launch of HBO Max.

Three months free: Existing customers on many video packages will be eligible for HBO and HBO Max for 3 months at no additional charge when HBO Max launches. But this excludes video customers on AT&T's lowest-tier plans such as DirecTV Family, U-Family, U-Basic and AT&T TV Now Plus.

Internet customers:

HBO Max at no added cost: HBO Max will be included with the AT&T Internet 1000 plan at no additional charge

One month free: Across other internet plans, new and existing customers can sign up for an HBO Max one-month free trial.

Wireless customers:

HBO Max at no added cost: HBO Max will be included in the AT&T Unlimited Elite wireless plan.

One month free: Across other wireless plans, new and existing customers on AT&T Unlimited Extra, AT&T Unlimited Starter and AT&T Mobile Share plans can sign up a one-month free trial.