What is coordination of benefits (COB) in Canada?

Coordination of benefits (COB) is a process used when a person is covered by more than one group benefits plan — most commonly when both spouses have workplace health and dental insurance. COB rules determine which plan pays first (primary) and which pays second (secondary) so that the combined reimbursement does not exceed 100% of the actual expense. Without coordination rules, insurers would face duplicate payments and would price group coverage much higher. The coordination process: claim to the primary insurer first for reimbursement; take the Explanation of Benefits (EOB) showing what was paid and what was not; claim the unpaid balance to the secondary insurer. The combined payout of the two plans cannot exceed the actual expense. COB rules in Canada are set by the Canadian Life and Health Insurance Association (CLHIA) guidelines, which most group insurers follow.

What is the birthday rule for coordination of benefits?

The birthday rule is used to determine which parent's plan pays first for claims made on behalf of dependent children. The rule: the parent whose birthday falls earlier in the calendar year (month and day — not year of birth) has the primary plan for dependent children's claims. Example: Parent A born March 15; Parent B born September 22. For their children's claims, Parent A's plan is primary (March 15 comes before September 22). Note: (1) The year of birth is irrelevant — only month and day are compared; (2) If parents share the same birthday (month and day), the parent who has been covered by their plan longer has the primary plan; (3) This rule applies specifically to dependent child claims — each adult's own claims are always covered by their own plan first. Some provinces or plan specifics may have minor variations, but the birthday rule is the standard Canadian industry practice.

Can I get more than 100% reimbursement with two plans?

No — coordination of benefits ensures that combined claims from two plans never exceed 100% of the actual eligible expense. CRA and insurance practice prohibit "profitable" insurance claims. Example: dental filling $300 — Plan A (primary) covers 80% = $240 paid; remaining $60 → submitted to Plan B (secondary), which covers 80% of $60 = $48; total reimbursement = $288 (96%). Even though Plan B's standard rate is 80%, it only pays 80% of the remaining unpaid amount, not 80% of the original total. In some cases (particularly for drugs or dental), the combined result can reach or approach 100% of the eligible expense — but never exceed it. The combined ceiling is the lesser of (a) the actual expense or (b) the sum of what each plan would have paid independently.

How do I submit a claim to two insurance plans?

The process: (1) Submit your claim to your primary plan first, through your primary insurer's app, portal, or by mail. (2) Receive your Explanation of Benefits (EOB) — a statement showing what was approved, what was paid, and the reason for any unpaid portion. (3) Submit the original claim plus the EOB to your secondary insurer. Many insurers allow electronic submission if your provider can electronically bill your secondary. (4) Receive the secondary payment — the secondary covers all or part of the remaining eligible amount, up to 100% of the original expense. For dental claims, dentist offices often coordinate this for you electronically. For paramedical (physiotherapy, massage, etc.), you typically coordinate manually. Always keep both providers' plan numbers and insurer contact details easily accessible.

Is it worth keeping two separate employer plans or should one spouse opt out?

Whether to keep dual coverage depends on the premium cost of each plan and your household's actual claims. If both plans are employer-paid (employee pays nothing), maintaining dual coverage is almost always worthwhile — you maximize reimbursement at no extra cost. If one plan requires a significant employee premium contribution (e.g., $150/month), calculate whether your additional reimbursement from secondary coverage is worth the premium. Rough test: if your family consistently has $3,000–$5,000+ in annual extended health and dental expenses, dual coverage likely pays off even with a $100–$150/month secondary premium. If you rarely use benefits and pay nothing for the secondary plan, there is no reason to opt out. Opting out to avoid one plan's employee premium is only rational if the premium exceeds expected secondary reimbursement — run the math with last year's actual claims.

Coordination of Benefits Canada 2026 — How Dual Coverage Works

How Coordination of Benefits Works — Step by Step

Step	Action
1. Determine primary plan	Your own plan is always primary for your own claims; use birthday rule for children
2. Submit to primary	File claim through primary insurer (electronic or paper)
3. Receive EOB	Explanation of Benefits shows amount paid and unpaid eligible balance
4. Submit to secondary	File for the unpaid balance with your EOB attached
5. Receive secondary payment	Secondary pays eligible portion of remaining balance — up to 100% combined total
6. Neither plan overpays	Combined payout cannot exceed actual eligible expense

Determining Which Plan Is Primary

Claim Type	Primary Plan	Secondary Plan
Your own claim	Your own employer plan	Spouse’s plan (you as dependent)
Spouse’s own claim	Spouse’s own employer plan	Your plan (spouse as dependent)
Dependent child — birthday rule	Plan of parent with earlier birthday	Plan of parent with later birthday
Dependent child — same birthday	Plan of parent covered longer	Other parent’s plan
No employer coverage (one) + individual (other)	Group plan first	Individual plan second

Birthday Rule — Worked Examples

Example	Parent A Birthday	Parent B Birthday	Primary for Child Claims
Standard	March 3	September 14	Parent A (March 3 earlier)
Reversed	October 7	February 22	Parent B (February 22 earlier)
Same month, different day	April 12	April 27	Parent A (day 12 earlier)
Same day and month (different year)	June 5, 1982	June 5, 1985	Longer-covered parent
Single parent with two plans	N/A	N/A	Plan in effect longer is primary

Claim Reimbursement — How Combined Calculations Work

Example: Dental Filling — Actual Cost $300

Plan	Coverage Rate	How Applied	Amount Paid
Plan A (primary)	80% of eligible	80% × $300	$240
Plan B (secondary)	80% of eligible	80% × remaining $60	$48
Total reimbursement			$288 (96%)
Out of pocket			$12 (4%)

Example: Prescription Drug — Actual Cost $180; each plan covers 80%, $5 dispensing fee not covered

Plan	Coverage	Applied to	Amount Paid
Plan A (primary)	80% of $175 after fee	(eligible = $175)	$140
Plan B (secondary)	80% of remaining $35		$28
Total reimbursement			$168 (93%)
Out of pocket			$12 (7%)

Example: Paramedical (Physiotherapy) — Actual Cost $120; Plan A limit $80; Plan B covers 80% up to $100

Plan	Details	Amount Paid
Plan A (primary)	Covers $80 max per visit	$80
Plan B (secondary)	80% × remaining $40	$32
Total reimbursement		$112 (93%)

What Both Plans Cannot Exceed

Principle	Rule
Combined payout ceiling	Lesser of (a) actual eligible expense or (b) sum of what each plan independently would have paid
“100% rule”	Plans may not together reimburse more than 100% of actual eligible expense
Overcharge scenarios	If a dentist charges above reasonable and customary fees, neither plan covers the excess
Government plan first	If provincial plan (e.g., OHIP+ for under-25) covers some drugs, both group plans coordinate after provincial coverage

Annual Planning — Do the Math

Household Claim Level	Annual Secondary Reimbursement Estimate	Worth paying $100/month for secondary?
Low ($500/year total)	~$50–$100	No (cost = $1,200/year)
Moderate ($2,000/year total)	~$200–$400	Borderline
High ($5,000/year total)	~$500–$1,000	Yes
Very high ($10,000+)	~$1,000–$2,000+	Clearly yes

Practical Tips for Maximizing Dual Coverage

Tip	Benefit
Keep both plan numbers and insurer contacts documented	Faster claim submission
Request electronic billing at dental/vision — many offices do secondary auto-submit	Less manual work
For large anticipated expenses (major dental, paramedical series), calculate both plans first	Avoid surprises on balance owing
Confirm annual maximums on both plans at start of year	Know which to file first for expenses near the maximum
Coordinate drug claims — some drug plans override each other for generics	Maximize coverage by submitting to right plan first