January is the busiest month of the year for officials at the Washington State Department of Revenue, when as many as 490,000 tax returns come due for monthly, quarterly and annual filers.

Every annual filer in Washington state, even those who had no business activity in 2013, must file tax returns with the department by Jan. 31, according to state officials.

The revenue department offers several options for taxpayers to file returns on time:

– Call and talk to the revenue department’s tax specialists: 800-647-7706. Callers can reach the department’s tax specialists between 8 a.m. and 5 p.m. every weekday. Automated phone services are available 24 hours a day.

– Email tax questions. Revenue officials generally provide responses within two business days.

– Visit one of the department’s offices located across the state.

Around 90 percent of businesses that file monthly or quarterly use the department’s electronic filing system. But officials say some businesses are only required to file a tax return annually and may need assistance whether they file electronically, by phone or by mail.

More tips for annual filers are on the department’s website.