We all live busy lives. Jobs to do, kids to look after, bills to pay. On the list of people's day to day priorities, I totally get that registering to vote might not be top of the list.
But the simple fact is that if you aren't down on the list you can't exercise your right to vote. And in just three months there is likely to be a closely fought General Election. It could be your vote that makes the difference in your area - after all, in 2010, a handful of seats had majorities of less than 100.
I understand that people are disillusioned with party politics. I get that the Westminster bubble is a turn off for many voters. And that means people don't bother registering, as they don't want to vote. I don't for one minute want to make light of the task for elected politicians to show we are in tune with people's lives, we get what issues concern them, and that we are able to do something about it.
Yet fewer and fewer people are having a say in the future of our country. The register isn't perfect. It isn't an exhaustive list of everyone, it's not even a list of all those eligible to vote. Registration is an active process - you have to fill in a form, or go online in order to apply to be on the register.
That means people fall by the wayside. Some people don't have the luxury of living in one place for a long period of time, and the hassle of re-registering time and again is a chore. We know that a lot of younger people just think it's not important. Students have other things on their minds in fresher's week. Language and disabilities might be barriers for others.
It all adds up to a whopping 7.5million people missing from the register. Just think that through - that's the equivalent of ten cities the size of Sheffield who are missing from our electoral register. It adds up to the same number of people that live in 100 parliamentary constituencies!
But being on the electoral register is about way more than just voting in elections. It's about civic responsibility and it's about people's quality of life. If you want to borrow money, or get a mortgage, one of the first things the bank will check is your credit rating and that's linked directly to whether you are on the electoral register. Our justice system relies on trial by jury - and members of those juries are randomly drawn from the list of those registered to vote.
If it wasn't bad enough that so many were already missing from the register, the system is going through the biggest change in living memory. A million more voters have disappeared in the last 12 months. And as Ed Miliband has warned today, there has also been a sharp drop in the number of first time voters on the register
This shouldn't have come as a surprise to Ministers - plenty of experts were warning this would happen. But they did nothing to prevent it, and seem clueless about what to do to repair the damage. Just yesterday in the House of Commons, in a debate called by Labour, Ministers demonstrated a shocking level of complacency. And we know that the same kinds of groups that are already unregistered are the same ones going missing.
Imagine the impact of this. Imagine trial by jury - suddenly no longer trial by one's peers, but trial by a sub-group of one's peers. Imagine millions of people unable to access credit, or prevented from buying a house. Imagine the questions over the legitimacy of a parliamentary boundary review, done using a register missing more voters in some areas than others.
That's why we must do more to reach under-represented groups. We need to persuade them the value of being on the register. We must make it easier for people to sign up. We should remove obstacles that make it a chore. We need block registration for universities and colleges. We should implement a schools registration scheme for those approaching 18 requiring schools to pass on information to electoral officers. Local authorities should use the wealth of data at their disposal to automatically register people to vote.
Without the hard work of many campaign groups, I hate to think what state things would be in today. I take my hat off to Bite the Ballot for organising today's National Voter Registration Day. And I pay tribute to Hope Not Hate, Operation Black Vote, trade unions, churches, mosques and other faith groups who've done lots to sign people up.
So if you do one thing today, make sure you're registered. Don't give political parties an excuse to ignore you, your family, friends and work colleagues. See it for what it is, a civic duty which has wide-reaching ramifications beyond ballot boxes and polling day. But there's only three months left until the election so if you want your voice to be heard and you want to have a say in your future, get online and fill in the form before it's too late.
Go to gov.uk/register-to-vote to get registered.
Sadiq Khan MP is the Shadow Justice Secretary (with special responsibility for political and constitutional reform)