In most cases, it is up to the voter to pay for postage to return an absentee/mail ballot envelope to the election official. Some see this as a barrier to returning a ballot, or as a type of poll tax. One solution to this potential issue is to have ballot drop boxes widely available. In states that hold all-mail elections, returning by drop box or in person is the most common return method. Another option is for election officials to pre-pay postage for voters to return their ballots.
Nineteen states and Washington, D.C., require local election officials to provide return postage for mailed ballots. This is typically a business-reply mailing, so that local officials only pay for return postage for the ballots that are actually returned via the U.S. Postal Service. Note: New Jersey leaves it up to the discretion of county clerks to provide a postage-paid envelope (N.J.S.A. 19:63-12).
It's important to note that the U.S. Postal Service has a policy of prioritizing election mail, especially ballots, and will deliver a ballot envelope even if it does not have sufficient postage. Typically, though, the post office will bill the local election office for the price of postage. If the majority of voters don't affix postage, this could be a significant expense for a local election office.
For military and overseas voters, federal law specifies that ballots can be returned to election officials using a free postage-paid symbol when mailed from a U.S. Post Office, Military Postal Service Agency (APO/FPO) or U.S. Diplomatic Pouch Mail. However, if voters return the ballot through a foreign mail system or via common carrier (such as FedEx, DHL or UPS), they must pay the rate for that service themselves.
The table below provides details and citations for the 19 states and Washington, D.C., that provide postage-paid envelopes to voters.