In theory, that gives him six more years in power, and the right to run for a further six-year term after that (he got around the constitutional ban on more than two consecutive terms as president by spending the past four years as prime minister).
But it's very unlikely that Mr Putin will be ruling Russia 12 years from now.
The latest opinion poll predicts that Mr Putin will win 66% of the votes cast on Sunday but he's lucky that the presidential election is happening now and not a year from now, because his support is eroding fast. People are losing their fear of his regime, and the corruption issue is biting deeper and deeper.
Recent street demonstrations in Russia's big cities are important but the occasional outbreaks of open mockery of Mr Putin in the media are an even better indication of which way the wind is blowing.
A case in point is Ksenia Sobchak, one of Russia's most popular bloggers, whose television talk show Where Is Putin Taking Us? was cancelled after the first episode because she invited protest leader Alexei Navalny on the show.
She struck back with a video mocking celebrities who have recorded messages endorsing Mr Putin's election campaign. It opens with a close-up of a rather bedraggled looking Ms Sobchak earnestly urging Russians to vote for Mr Putin.
"Now is not the time to rock the boat and we should rally round one leader," she concludes; the producer shouts "cut" and the camera pulls back to show she is tied to a chair and flanked by armed guards.
Mockery is an effective weapon because it undercuts people's fear of speaking out, but it's corruption that is really damaging Mr Putin's standing.
The corruption is not personal: Mr Putin made his pile in the first few years after the collapse of the Soviet Union, as has been amply documented in Masha Gessen's brave and meticulously researched new book The Man without a Face: The Unlikely Rise of Vladimir Putin.
He has no need to steal any more.
However, turning a blind eye to corruption has become the main way that Mr Putin's regime gains and keeps collaborators.
As one of his ex-KGB former collaborators from St Petersburg, Viktor Cherkesov, told the Spanish newspaper El Pais last October, "Putin doesn't pay much attention to theft, because he reckons everyone steals."
Most people who work for his regime do indeed steal - but the public is paying attention, and slowly but surely it is drawing conclusions, even in the slumbering heartland of Russia.
Mr Putin lives in fear of another "colour" revolution like the Orange one that swept away the former Ukrainian regime or the Rose Revolution in Georgia, but when the time comes in Russia it won't take a revolution to change things.
The country is already a democracy in form, and to a certain extent in substance, too. Mr Putin actually has to get elected, and he can only go so far in trying to bend electoral outcomes to his will.
For 12 years Mr Putin has ruled Russia almost without challenge, partly because of his macho image and partly because he has overseen a rise in living standards - due in part to a steep rise in oil prices. His tough-guy image still appeals to some, but it is getting old.
The economy, for reasons largely beyond Mr Putin's control, is no longer producing dramatic growth. As a result, United Russia, Mr Putin's own party, fell below 50% of the votes for the first time in last December's parliamentary election.
It might have fallen further if not for large-scale fraud in the counting of the votes. That fraud triggered the first major protests since Mr Putin came to power, and the regime has been forced to retreat on several fronts.
Regional governors will once again be elected directly (before, Mr Putin was appointing them) and it will become significantly easier to register new political parties in Russia.
Mr Putin is demagogic, cunning and ruthless, but he is not actually a dictator and his regime is more fragile than it looks.
If it loses popular support, the question is not whether it will also lose power, but only when. Will Russians be willing to wait six years until the next scheduled presidential election, or will they find a (hopefully legal) way to push him out a good deal sooner?
- Gwynne Dyer is an independent London journalist.
