Question: How much postage is needed to send my mail-in ballot? According to the USPS, completed ballots are classified as First-Class Mail and require proper postage to help ensure timely processing and delivery. Voters are responsible for affixing the appropriate postage on their return ballot envelope. According to Texas Tribune, postage for mail-in ballots will vary by the county due to differences in the ballot style and size. The First-Class Mail postage rate for a standard-sized, rectangular envelope starts at $0.55.