You should do some preliminary market research in order to have a good discussions with BC Assessment.

For detailed suggestions see the Guide: Preparing Submissions on the Market Value of your Property. At this negotiation stage, you do not have to conduct all the in-depth analysis that is listed there. The Guide will, however, help you with:

• where you can research sales; and
• what type of support you will need, if you do not settle your appeal in the Online Dispute Resolution (ODR) website.

For an effective online discussion with BC Assessment, we suggest, at a minimum, you provide the following:

• List of sales of properties similar to yours. Include:
  • Address of the sale
  • Date of the sale 
  • How this property is similar to yours (location; size of land; size, age and condition of house; other characteristics (e.g. waterfront))

Look for sales that occurred last year. This is because your assessment should be at your property's value as of July 1 last year.

Notes:
It is acceptable to use sales that are months before or after the July 1 valuation date. The farther away from the valuation date, the more likely the sales will need to be adjusted for any market changes during this time frame.

You should also review the material in Do I have a strong case.