This post was updated on Friday, Oct. 30 at 10:50 a.m.

Remember: If you haven't submitted your ballot yet, at this stage it's recommended you submit it by hand at a drop box specifically for vote-by-mail ballots, rather than using a USPS collection box. You can also return your ballot in person to a drop-off location, your county election office or to any voting site up to Election Day at 8 p.m. Find your nearest drop box.

We know, you don't need more uncertainty in 2020.

But if you're new to voting by mail, or just want to make extra-sure your vote is counted in the 2020 election, you might be wondering how best to fill out your vote-by-mail ballot to make absolutely sure it gets counted — and isn't rejected.

This year, because of the COVID-19 pandemic, every registered voter in California received a mail-in ballot without requesting it in an attempt to avoid crowding at the polls. And yes, sometimes voters make mistakes filling out their ballots that lead to those ballots being initially rejected.

But the good news is that not only are those mistakes avoidable, but there's an entire system designed to flag and help you rectify those mistakes quickly so that your ballot can be counted. You can even sign up to track your ballot's progress and be alerted to any problems.

Skip straight to:

• Common signature errors
• What if I make a mistake on my ballot?
• My ballot isn't here yet. When do I worry?
• Find your county's info

We spoke with Kim Alexander, president of the nonpartisan California Voter Foundation, about the errors to avoid when filling out your ballot so that you can get your vote on its way to being counted.

• Ask us: What do you want to know about voting in the Bay Area for the 2020 election?

Plan to Send Your Ballot on Time

Before we even talk about what's on the ballot itself, you need to know this: The #1 reason that ballots get disqualified in California is because they aren't mailed on time.

In order to be counted, your ballot must be mailed and postmarked on Election Day at the latest — and the deadline for mail-in ballots to be received has been extended to Nov. 20 (from Nov. 6.) But, Kim Alexander says, the problem isn't usually ballots arriving too late; it's that they're being postmarked too late. And it's not necessarily a case of people sending them after Election Day.

The more likely problem is that some people are just sending them too late in the day on Election Day itself, says Alexander. Officials know this, she says, because the majority of those ballots that have previously been too late to count have been postmarked on the day immediately after Election Day: "which tells us that people likely put their ballots inside mailboxes that had already been picked up, or took them to post offices that had already closed for the day," she says.

The issue of lateness is exactly why it's recommended that voters return their ballots early, Alexander says.

The United States Post Office recommended mailing your ballot no less than one week before Election Day — so if you're reading this a few days before Nov. 3, and you haven't submitted your ballot yet, at this stage it's recommended you submit it by hand at a drop box specifically for vote-by-mail ballots, rather than using a USPS collection box. You can also return your ballot in person to a drop-off location, your county election office or to any voting site up to Election Day at 8 p.m. Find your nearest drop box or voting location.

Regardless of when you submit your ballot, it will be counted only after polls close on Election Day.

Got Your Ballot? First, Read the Instructions

No seriously, read the instructions. From skim-reading the terms and conditions on your phone's updates to sorta-just-guessing how to assemble IKEA furniture, we're all sometimes guilty of skipping over information and instructions — but this is the time to take the extra minutes, and carefully read the instructions on your ballot. Even if you think you know them or remember them from last time, it's worth it.

The instructions will remind you to:

• Use the right pen (blue or black — no other colors)
• Mark your votes in the correct places (within the designated oval)

Your ballot's instructions will also tell you how to correct a mistake on your ballot. These guidelines can differ from county to county.

Sign Your Ballot — Correctly

When you're done filling out your ballot, you must sign the envelope. But the two big mistakes people make with their signatures are:

• Forgetting to sign their ballot entirely, or...
• Making a signature that doesn't match the signature they made when they registered to vote

Why wouldn't your signature match the one on file? If you registered to vote at a young age, maybe your signature has changed over time. Or perhaps you registered to vote at the DMV and provided your signature on a screen with a stylus, which doesn't quite replicate how you'd make your signature with a pen, on paper.

If you registered this way, one simple way to avoid any signature problems is to take a quick glance at the signature that's on your driver's license or state I.D. — because that's the one you want your ballot signature to match.

Even if you didn't register at the DMV itself, that signature on your most recent license or state I.D. is still very likely the one to emulate. That's because when you register to vote online, your county elections office electronically requests a copy of the signature the DMV currently has for you, and this information is regularly updated.

To further set your mind at rest, know that California isn't an "exact match" state, and doesn't demand voters' signatures 100% replicate the signature that's on file. We've got even more information about signature matching here.

What if you still get it wrong?

Luckily, there's a whole system in place to help you correct your mistake. If your county's election office detects a signature mismatch on your ballot, they'll reach back out to you via mail to verify and work with you to correct it, so that your ballot can be counted after all. (This system is also applied when it looks like a member of a voter's family might have signed their ballot, instead of the voter.)

There's "actually quite a long period" allowed for this signature "curing process," Alexander says. Counties have to contact voters at least six days before they certify their election results and give voters up until two days before they certify their election results to "cure" their signatures. And remember: sign up to track your ballot, and you'll find out about any issues with your ballot or your signature quickly.

By the way, here at KQED we've had several audience questions asking whether the date required on the signature section should be the date you signed your ballot, or your birthdate. It's the first one: the date you signed it.

Don't Mail an Empty Envelope

Sounds unlikely, maybe, but it happens. According to The Associated Press, more than 800 envelopes were mailed in California's March primary without any ballots inside.

Keeping your envelope and your ballot together in your home might be a helpful way of avoiding this problem. And of course, when you're ready to mail your ballot, make sure it's actually inside the envelope before you seal it.

What if You Make a Mistake on Your Ballot?

First, don't panic.

People make mistakes on ballots, and find good ways to correct them. Counties give different directions to voters about what to do if they make a mistake (remember: read the instructions!) but you can usually simply "X" out the choice you didn't intend, Alexander says, and put in your correct choice. (More information about correcting mistakes.)

"Voters do all kinds of creative things with their ballots," she says, and the job of county elections officials — once they've verified your signature — is to make sure your ballot can be read correctly. If that means that your corrections on your ballot have resulted in readability issues, officials working in teams of two will actually remake it for you according to the intent you've signaled with your corrections.

What if you don't feel you can fix your mistake, or you've somehow damaged your ballot (or straight-up just spilled coffee on it?)

Alexander says you have multiple options:

• Call your county elections office and ask them to cancel that ballot and issue a new one to you
• Go to your county elections office with your spoiled ballot and vote right there at the counter during business hours
• Take advantage of the early voting options available in many counties
• Go to a voting site on Election Day, turn in your spoiled ballot there and get a new ballot

What if You Didn't Get a Ballot at All?

If you aren't registered to vote in California, you won't be sent a ballot automatically. If you didn't register and decide you want to vote in person, you can register via what's called Same Day Voter Registration (also known as Conditional Voter Registration.) If you're doing this on Election Day itself, you can register and vote at the same time at your polling place — find your voting location here. The deadline to register online to vote is October 19.

If you are registered to vote, ballots will be sent out in California by October 5 — so you should expect to receive your ballot by around October 15, Alexander says. This is another good reason to sign up to track your ballot's progress, and be reassured if it's on the way.

What if there's no sign of your ballot? Again, Alexander says, don't panic, because "there are a lot of fail safes in the system."

One helpful warning sign, Alexander says: "If you're not getting anything about the election in the mail, you probably aren't registered to vote at your current address." Check your registration details and address, and if they're incorrect, update them ASAP before the voter registration deadline of October 19, 15 days before Election Day. Your county elections will then cancel any previous ballot mailed out so that it won't be counted, and send you a new ballot.

Your county election office won't mail you a ballot six days or less before Election Day, because it can't be sure it'll reach you in time. So if you're trying to get a ballot in the immediate run-up to November 3, go to your county elections office in person and request one at the counter. And remember, you always still have the option of Same Day Voter Registration, a.k.a Conditional Voter Registration at a voting location, where you can then fill out and submit your ballot, too.

What if You Use Assistive Technology to Complete Forms?

Remember, getting physical assistance with filling out your ballot from someone you trust is always fine, whether you're voting at home or at a voting site. You just need to make sure your signature is your own, and matches the one you're registered to vote with.

Voters with disabilities can also choose to use the Remote Accessible Vote-By-Mail system to vote privately and independently at home, using their usual assistive device on their home computer to fill out the ballot on their screen and then print and mail it. (This year, Remote Accessible Vote-By-Mail is actually available to all voters who need it, under emergency legislation passed earlier this year in light of COVID-19.)

Every voting location in California is also equipped with an accessible voting unit. Here, voters who are sight-impaired or have a disability that limits their dexterity will be able to use the assistive device of their choice that allows them to vote privately and independently.

Tip: Look Out For the Young Voters in Your Life

Young voters are the most likely to have their ballots rejected, according to the data — and there are good reasons for that, Alexander says.

Most obviously, they're newer to voting in general. But they're also likely to be less familiar with how the U.S. Postal Service works, especially when it comes to issues like collection times and post office hours. Younger people are more likely to conduct a lot of their business online, and therefore have less familiarity with activities that require a written signature on paper, like writing checks.

Younger voters, Alexander says, also get their ballots rejected more frequently than other voters due to signature mismatch. Why?

"We think that's really stemming from the fact that many of them are pre-registering to vote, or registering at a very young age before they've actually formed a signature," she says — especially if they're making that signature with a stylus while registering at the DMV. Her advice, once again: Check the signature on your driver's license or state I.D., and make sure it matches what you're signing on your ballot.

All this, Alexander says, means younger voters "have a knowledge gap there that they have to overcome." So if you're able to spend five minutes helping out a young person in your life who wants to vote this year, it's time well spent. (Or just send them this article.)

And remember: if a 17-year-old will be 18 by Election Day, they can vote in the 2020 election — because that's when their vote is actually counted. Pre-registering to vote now (here) will ensure their registration becomes active on their 18th birthday.

CHECKLIST: Before You Mail or Drop Off Your Ballot...

• Have you clearly corrected any mistakes?
• Have you signed it?
• Does your signature match the one you're registered with?
• Have you put your ballot in the envelope?

Find Your County's Info on Marking Your Ballot

• San Francisco
• Alameda
• Santa Clara
• Contra Costa
• Solano
• San Mateo
• Marin
• Napa
• Sonoma

Tell us: what else do you want to know?