If you plan to switch to AT&T for a new smart phone or wireless tablet contract, do it now. After January 22, AT&T’s monthly wireless data plans get more expensive by $5. If it’s any consolation, you do get up to one additional gigabyte of data.

According to AT&T’s official release, new smart phone customers will have a choice of three new monthly data plans—300MB for $20, $30 for 3GB, and $50 for 5GB, including the ability to share the wireless data connection with other devices. The 3GB and 5GB monthly plans will also be available to new subscribers with tablets that have 3G wireless data modems built-in. Go over you’re monthly allotment and AT&T will charge you an extra $10 per additional gigabyte or $20 for 300MB if you’re on the lower plan.

Current subscribers can keep their existing data plans—$15 for 200MB, $25 for 2GB and $45 for 4GB, which also includes tethering. But once customers make a switch to the new pricier plans, they can’t go back. And after Jan. 22, the existing $15 for 250MB monthly plan for tablets will be the only old plan still offered–and only to new tablet owners subscribers.

Is the additional gigabyte of data worth the extra $5 per month? Check out Consumer Reports’ buying advice on mobile phones and services for more information on how to decide.

AT&T Launches New Data Plans [AT&T press release]
AT&T to adjust data plans January 22nd, offers more gigs for more money [Engadget]

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