Thousands of low-income B.C. seniors missed out on important federal benefits because they didn't file an income tax form, B.C.'s Seniors Advocate says.

With the April tax deadline approaching, Isobel Mackenzie has reminded seniors that 13,000 B.C. residents were found in a national survey to have missed out on the Guaranteed Income Supplement for as much as seven years. Once identified, seniors received retroactive payments from Ottawa.

"GIS is a key support for the lowest income seniors," Mackenzie said. "These are seniors living on $17,300 annually or less; however to receive this GIS you must file an income tax return."

Other B.C. senior benefits that require tax filing include Shelter Aid for Elderly Renters (SAFER), a subsidized BC Bus Pass for seniors receiving GIS, and Medical Services Plan premium assistance for low-income B.C. residents.

Co-payments for home support service are also waived for seniors receiving GIS, and publicly funded residential care and assisted living rates are calculated based on after-tax income.

Volunteer income tax clinics hosted by community agencies in B.C. offer free tax preparation. A list of free tax preparation services is available or by calling the office of the Seniors Advocate at 1-877-952-3181.