"All major issues have been solved," spokesman Andrej Cirtek told AFP, adding that the centre-right Czech government could be expected to discuss the proposed Status of Forces Agreement (SOFA) in September.
A key follow-up agreement had been held up by a wrangle between Prague and Washington over the tax treatment of the proposed U.S. radar.
That issue has now been resolved, Cirtek said, but refused to give details. Final touches to the wording of the proposed text are being worked on in Czech and English, he added.
Sealing the SOFA agreement would clear the way for Prime Minister Mirek Topolaneks fragile government to seek the required parliamentary approval for the U.S. anti-missile package.
"It appears that it could be dealt with during the September session of parliament," vice premier and Minister for European Affairs Alexandr Vondra told Tuesday's edition of the Hospodarske Noviny business daily.
The main deal on the base, justified by Washington as a shield against attack from "rogue" states such as Iran but vigorously opposed by Moscow as a threat to its own security, was signed by U.S. Secretary of State Condoleezza Rice and Czech counterpart Karel Schwarzenberg in Prague last July.
A few weeks later, Poland inked a deal with the U.S. to host 10 interceptor missiles, its contribution to the missile defense shield, sparking anger and threats of retaliation from Russia.
Topolanek’s government is far from certain of winning a vote for the U.S. base.
Members of the junior coalition party, the Greens, have spoken out against it and the third coalition party, the Christian Democrats, are also cool to the idea.