Natural Disaster and Emergency Ballot Act of 2020 This bill revises and establishes voting procedures for federal elections. Specifically, the bill requires each state and jurisdiction to, within 30 days, establish and publish a contingency plan to enable voters to vote in federal elections during an emergency. Such plan must (1) include initiatives related to the safety and recruitment of poll workers, and (2) permit registered voters to submit online requests for absentee ballots and vote by mail or by drop-off location. Additionally, for all federal elections, a state must ensure that voters have 20 days to vote through early in-person voting or by mail; begin processing ballots cast during early voting or by mail at least 14 days before the date of the election; provide self-sealing return envelopes with prepaid postage for voter registration applications, absentee-ballot applications, and blank absentee ballots; allow voters to cure certain signature discrepancies; accept voter registration applications at least 21 days before the date of the election; and provide certain accommodations to voters residing on Indian lands. The Election Assistance Commission (EAC) must create a uniform domestic downloadable and printable absentee ballot for use in federal elections. Until the EAC creates such a ballot, states must permit certain voters to use those ballots provided to overseas and military voters. The Cybersecurity and Infrastructure Security Agency must create an update service to inform voters of their voter registration applications, absentee-ballot applications, and absentee ballots. States must be reimbursed for implementing the provisions of the bill.