Typically, a financial institution will not accept a post-dated check. Attempts to deposit it before the date on the check will probably be futile, if the teller is paying attention to detail.
Also, there is no gift tax on gifts under 11.2M, and I doubt you have a check for that much. However, there is a reporting requirement for gifts more than $16K in 2022, and that rises to $17K for 2023. The recipient of the gift is not required to do or report anything. Ever. However, if the gift exceeds $17K (for 2023) then the giver (not the recipient) is required to file IRS Form 709 - Gift Tax Return with the IRS. Again, if the gift is less than $11.2M then even the giver will not pay taxes on it. (The money they gifted you has already been taxed.) But the giver is "required" to report it if it exceeds the $17K threshold for 2023. For the giver, it's just a reporting requirement, and that's all.
