The US government seeks to intervene in Apple's appeal against a European Union order to pay up to €13bn (£11.4bn) in Irish tax.
In September 2016, Apple CEO Tim Cook said he would appeal against the European Commission's ruling that claims the company received a €13bn subsidy when Ireland gave the company preferential tax deals.
Following this, Apple filed a court appeal in the General Court in Luxembourg in December after the European Commission issued a tax demand saying Apple won the tax deal from the Irish government, Reuters reports.
Criticising the decision the Obama administration said the European Union was helping itself to cash that should have been in the US.
"I can confirm the United States filed an application with the European Union General Court to intervene in the case involving the retroactive application of state aid rules to Apple," a source told Reuters.
The court is expected to hear the case in late 2018.
Apple said it was a convenient target and the EU competition regulators used an "absurd theory" to come up with a punitive figure.
The EU is also after Amazon and McDonald's over their tax deals with Luxembourg.
Ireland, the Netherlands, Luxembourg, Starbucks, Fiat Chrysler Automobiles and several other companies that were ordered to pay taxes to EU countries have also challenged their EU rulings.