The IRS posted drafts of the forms that employers will have to fill out to comply with the Obamacare requirement that employers provide health insurance to workers.

Some business groups said the information was still too tentative and too incomplete to let them prepare for new obligations under the health law. “Our immense frustrations with the IRS continue,” Christine Pollack, vice president of Government Affairs at the Retail Industry Leaders Association, said in a statement.

An administration official said the White House is sticking to the timeline announced earlier this year. Companies with 50 to 99 employees will have another year — until 2016 — to start the coverage. Companies with 100 or more employees do have to comply next year, although they have two years to phase up so that they are covering 95 percent of their workers. Smaller businesses are exempt.

The House Republicans are planning to sue President Barack Obama, saying he overstepped his authority in delaying the employer mandate. The GOP opposes the policy and has voted to repeal it, but Republicans still say it’s a prime example of presidential overreach.

The business community has been complaining about the complexity of the coverage rules and the lack of specifics. The draft forms the IRS released Thursday were more streamlined than the agency had earlier indicated. Three categories of information have been dropped. Employers can do a one-time checkoff for people covered year round, instead of filling out reports for everyone every month. And self-insured employers — those that assume the whole cost of their coverage — will fill out one form, not two.

However some business groups still had their worries, particularly as the instructions won’t be published until next month.

“The IRS only released draft forms, with no instructions or technical specifications. For the longest time, retailers have been pounding their heads, asking for this information from the IRS in order to get their systems up and running and comply with these requirements beginning this January. Yet again, it’s too little, too late for employers,” Pollack said.

The administration has estimated that the mandate will only apply to about 4 percent of employers. Most larger firms already offer health benefits.