It sounds like the chances of this are pretty low. But you can't be too careful these days.
Apparently, you shouldn't abbreviate the year "2020" by just writing "20" on checks and documents. Because if you do, it could open you up to SCAMMERS. Here's how . . .
If you write today's date as "1-6-20," it's easy for someone to change the year by adding two more digits at the end.
For example, you could write a check with today's date on it, and someone could deposit it electronically. Then they could add "21" to the end of the year, so it says, "1-6-2021." And they could attempt to cash the same check NEXT year.
Be careful with any contracts you sign too, because they could be doctored to make it look like the contract began sooner than it did.
Here's another example: Say you signed a contract today for a loan, and wrote "1-6-20" as the date. If you end up missing a payment, the lender could theoretically change the date to "2019", and claim you owe an extra year's worth of fees.
Again, it probably won't happen. But just to be safe, you might want to take the extra half-second to write all four digits this year. Then you can go back to using two digits in 2021.