I noticed that my broker allows me to contribute to both 2020 and 2021. I have already maxed out my 2020 IRA contributions. Since I cannot deduct anything from my income via these contributions due to my income I thought it would be wise to start to contribute to 2021 as well. Since my employer does not extend a retirement plan to me I don't really have any other options.
I couldn't find any regulations on the IRS website that prevent this. The only regulation I could find was available here, and it says I can only contribute a maximum of 6,000 to either a roth or traditional IRA, and only 6,000 for a given year. It is not clear whether this is the current year (as in 2020) or the notated year (6,000 for 2020, 6,000 for 2021).
Is this possible? Are there any downsides?