WASHINGTON - The sixth-month nuclear deal announced in November is finally ready to go into effect, Secretary of State John Kerry announced today.

For months, U.S. and Iranian technical negotiators have been hammering out what, exactly, each side is obligated to do over the six-month agreement. Negotiations in Geneva broke off in mid-December.

But the U.S. and Iran finally do have a deal: The six-month interim agreement will kick in on Jan. 20, Kerry announced today, after the under-secretary for political affairs - the U.S. official in brokering this deal - traveled to Geneva and met with Iranian and EU counterparts on Thursday, apparently laying the groundwork for the six-month clock to at last begin ticking.

"While implementation is an important step, the next phase poses a far greater challenge: negotiating a comprehensive agreement that resolves outstanding concerns about the peaceful nature of Iran's nuclear program," Kerry said in a written statement released to reporters.

Senior U.S. officials said Iran has agreed to allow International Atomic Energy Agency inspectors daily access at two of its major power plants, and the technical talks focused on what IAEA inspectors will be looking for when they visit and what information Iran will supply them.

On Jan. 20, Iran will no longer enrich Uranium to 20 percent and will dilute its entire stockpile over the course of the six-month deal and IAEA monitors will have access to Iran's centrifuges and the workshops where they're made, a senior U.S. official told reporters today on a conference call.

The IAEA will report at the beginning of Jan. 20 that Iran has not met its international nuclear obligations, and after that, the IAEA will report monthly on Iran's progress toward compliance with the terms of the interim deal.

In exchange, Iran will get about $7 billion over the course of the deal.

Once the IAEA confirms that Iran is following the terms of the deal, the U.S. will lift sanctions on Iranian petrochemical-product exports (but not its oil sales), its automotive industry, embargoes on aviation equipment and inspection services, and it will stop seeking to reduce Iran's oil sales to the countries that still purchase it at reduced levels.

The U.S. will also unfreeze $4.2 billion in blocked Iranian oil money in banks around the world, and dole that money out in installments over the course of the six months. In all, Iran will have gotten about $7 billion from those two measures combined.

Congress, meanwhile, continues to consider new sanctions, legislation President Obama has threatened to veto, and senior U.S. officials reiterated on a conference call today that the president would indeed block any bill imposing new sanctions on Iran during the six months.

In the Senate, more than 50 lawmakers have signed onto a bill that would implement new sanctions if Iran fails to comply with the deal or if no larger agreement comes of it.

The Nov. 24 agreement bars the U.S. from imposing any new sanctions during the six months of the deal, but not after it. Iran, however, has said that even a delayed or conditioned sanctions law would nullify the whole deal. The State Department, which has lobbied aggressively against any sanctions bill, has said it agrees.