There is no standard form I am aware of.
A simple letter titled SPECIAL ASSESSMENT with the info should suffice.
SPECIAL ASSESSMENT
$xx.xx per lot due on mm/dd/yyyy
On [date], in accordance with Article x, Section y of our [name of document] the board/membership voted in favor of a special assessment for the purpose of road maintenance.
Please send your payment in the amount of $xx.xx by mm/dd/yyyy to
Name of Association
Mailing Address
If there are any questions, please contact the Board of Directors at the address above or via email at
[email protected] For the Board
Name