Why hasn't Rita Skeeter registered as an Animagus?

Question

I mean after she got caught by Hermione. While being an officially known Animagus can be a downside to her work, not working at all is surely a bigger issue. We know she was forced to be unemployed:

Unemployment did not suit Rita. The hair that had once been set in elaborate curls now hung lank and unkempt around her face. The scarlet paint on her two-inch talons was chipped and there were a couple of false jewels missing from her winged glasses.

She could go to the Ministry and say she just had become an Animagus and be totally free from Hermione's blackmail. I don't think Hermione could actually prove Rita was an Animagus for ages before that.

Why did she choose to be unemployed and under a teenager's influence rather than being a free Animagus reporter?

Answer 1

The Ministry want to know about Animagii before they successfully complete the transformation.

"Your father and Sirius here were the cleverest students in the school, and they were lucky too, because the Animagus transformation can go horribly wrong — one reason the Ministry keeps a close watch on those attempting to do it."

My emphasis. This suggests you can't just rock up at the Ministry and say "I'm an Animagus, please register my animal and markings". The Ministry want to know up front, much the same as you can't just send a letter to your local government institution saying that you can drive. You need to register for a learner's permit and then do the tests.

There's additional information on Pottermore, that states

As you might imagine, you can’t just become an Animagus overnight. The learning process involves holding the leaf of a Mandrake in your mouth for an entire month, for example.

So, again the Ministry would expect a certain time to pass after registering your intention to try. All of which means that Rita would be in deep trouble if she tried to pretend she was learning, and Hermione outed her. Specifically being able to predict her animagus form and markings would give Rita some serious problems with pretending to be currently learning.

Answer 2

The things she did as an Animagus were debatably legal...

The thing about Rita Skeeter is she always goes for the Best stories possible, like when she sees Harry faint in Divination class, but Dumbledore had banned her from school grounds and if he had known she was an Animagus he would of used extra measures to keep her out.

"I found out how she was listening in on private conversations when she wasn't supposed to be coming onto the grounds," said Hermione in a rush.
_{^{- Harry Potter and the Goblet of Fire, Chapter 37 (The Beginning)}}

Also, i doubt that just if you're a Animagus you're allowed to creep around and spy/listen in on private conversations.

"There was a beetle on the statue the night we heard Hagrid telling Madame Maxime about his mum!" "Exactly," said Hermione. "And Viktor pulled a beetle out of my hair after we'd had our conversation by the lake. And unless I'm very much mistaken, Rita was perched on the windowsill of the Divinaion class the day your scar hurt. She's been buzzing around for stories all year."
_{^{- Harry Potter and the Goblet of Fire, Chapter 37 (The Beginning)}}

So her stories would lose their exclusivity if she registered. Her reputation would be lost and she might lose her spot as a Reporter for the Daily Prophet because she would then be publicly viewed as a sneak.

The sensationalist Daily Prophet reporter whom Dumbledore had banned from Hogwarts grounds managed somehow to wheedle her way back in by changing into her illegal Animagus form: that of a nasty little beetle. Appropriate enough for a journalist who scuttled merrily over the misfortune of others and fed on trash, you might say.
_{^{- Unregistered Animagi - Pottermore}}

Also i don't think that she figured out Hermione couldn't actually prove it, I think Rita thought that Hermione's word would be enough to convict her.

The punishment for being an unregistered Animagus was time in Azkaban so, when clever-clogs Hermione discovered Rita’s secret, the threat of exposure was enough leverage to make her stop writing those poisonous articles.
_{^{- Unregistered Animagi - Pottermore}}

Finally, Hermione's story makes sense, and there are people who would back it up, as @Holger mentioned she has probably used her ability as an Animagus to get good stories before, and people would wonder how she got those stories and if Hermione revealed to the public that Rita was an Animagus the public would think that her story made sense and support her case, eventually leading to the conviction of Rita.

Answer 3

It has already been established [by Hermione] that Skeeter uses her Animagus capability to spy on people in order to gather juicy 'news'. Registering now would mean that the fact that she is an Animagus, and the form she takes, would become public knowledge. People she would otherwise spy upon would be forewarned, and would look for her in that form before possibly divulging secrets. At the least, her effectiveness as a reporter would be compromised; at the worst, she would be at risk of having someone deliberately squash her like a bug!

Answer 4

Other, question-specific answers aside, Rita would be unlikely to get away with lying about her status as an Animagus, or when she became one. This covers both hiding the original achievement as well as making up a new story to fit her "sanitized" revelation.

Don't forget, wizards have access to tools that muggles can only dream of. Veritaserum alone more than destroys any plausible chance Rita might have of covering up the truth. Legilimency also exists and seems like a workable option, and in a real inquest her memories could be extracted and displayed with a Pensieve, obviously annihilating her deception.

And it's plausible enough that she would encounter a formal investigation (Hermione has enough pull with influential people at Hogwarts to nudge the government, loosely demonstrated with her ability to own a time-turner). Certainly Hermione wouldn't let her leverage disappear without consequences for Rita, strictly legal or otherwise.

Even if Hermione were unable to arrange a formal investigation, magical means of getting at the truth could probably still be employed to get the truth out through less official channels. The British wizarding community is pretty small, and social/professional rejection of Rita could be every bit as damaging as a legal judgment against her.

Finally, the point of her secretly being an Animagus wasn't to break the law arbitrarily, it was to get scoops without other people realizing someone was directly observing them. The secret being out, at any time and for any reason, would seriously degrade her ability to work in the mode we observe in the books. When you don't suspect anyone might be so disguised, you won't know to look for a beetle with odd markings on its head. People would suddenly stop talking any time they saw a beetle if Rita's secret were exposed.