OLYMPIA — With the deadline for annual tax filings just around the corner, the Washington State Department of Revenue (Revenue) is offering some tips to help businesses file their taxes on time.

January is the busiest time of year for Revenue, with tax returns all due from monthly, quarterly and annual filers. In all, Revenue could receive up to 518,000 returns this month – about half of those are expected to be from annual filers.

Every annual filer — even if they had no business activity in 2014 — must file a tax return with Revenue by Feb. 2.

The typical due date to file annual tax returns is Jan. 31, but because that date falls on a weekend this year, it has been extended to the next business day.

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.