January marks the busiest time of year for the Washington State Department of Revenue (Revenue), with tax returns all due from monthly, quarterly and annual filers. In all, Revenue could receive as many as 490,000 returns this month.

Every annual filer – even if they had no business activity in 2013 – must file a tax return with Revenue by Jan. 31, 2014.

Revenue advises business taxpayers to call with questions as early in the month as possible to avoid crunch time.

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

Revenue offers several options to help taxpayers file their return on time:

• Call and talk to Revenue’s tax specialists: 800-647-7706.

•  Email tax questions. Revenue generally provides a response within two business days.

• Visit one of Revenue’s offices located across the state.

Callers can reach Revenue tax specialists between 8 a.m. and 5 p.m. every weekday. Automated phone services are available 24 hours a day.

More tips for annual filers are on Revenue’s website.