RESP vs RRSP vs TFSA when you have kids and a mortgage

Before kids, the plan is simple: max the registered accounts, invest the rest. After kids, every dollar has four hands grabbing for it — retirement, education, the mortgage, and daycare — and the cash that used to fund “max everything” is suddenly spoken for. This isn’t a “which account is best” problem. It’s a sequencing problem.

The right question

People ask “which account is best?” The better question is:

What’s the next best dollar this household can deploy?

There’s no universal ranking, because the answer depends on your tax bracket, employer match, mortgage rate, the kids’ ages, and how tight monthly cash flow feels. The same family can have a different answer two years apart.

A strong default order

For many dual-income households, this is a solid starting sequence:

#	Where the dollar goes	Why
1	Employer match (e.g., group RRSP)	An instant 50–100% return — nothing beats it
2	RESP to capture the $500/yr CESG	A guaranteed 20% grant; usually beats prepaying a mortgage
3	RRSP — if your bracket is high	The deduction is worth most when your marginal rate is high
4	TFSA	Flexibility for medium-term needs and tax-free growth
5	Extra mortgage paydown	When the rate is high enough, or you value certainty

It’s a default, not a law — but it’s a defensible place to start before tailoring.

Where families get tripped up

Overcommitting to the mortgage

Attacking the mortgage feels safe, and emotionally it is. But if it means skipping the employer match, the RESP grant, or a high-value RRSP deduction, you’re trading a guaranteed 20–100% return for a guaranteed mortgage-rate return. The math usually loses.

Treating the TFSA as “just extra”

For families, the TFSA is often the best home for money you might need before retirement — and the flexibility is the point:

renovation or home-maintenance reserves
a job-transition cushion
medium-term family spending
optional early-retirement bridge money

Withdraw it and the room comes back the next year. No other account does that.

Assuming the RESP must be maxed first

The RESP’s sweet spot is the grant-capture range (~$2,500/yr). Past that, the marginal benefit usually falls below what an RRSP or TFSA dollar would do. Grab the grant; don’t race to the $50k lifetime limit at the expense of everything else.

What changes the order

Your sequence should shift if:

one spouse is on leave or earns much less (RRSP deductions are worth less this year — see parental leave planning)
a big comp jump is coming (defer RRSP room to a higher-bracket year)
your mortgage rate is unusually high
a workplace pension is already doing the retirement heavy lifting
the kids are older and the education timeline is short

The planning lens

A household with kids doesn’t need the mathematically perfect answer. It needs one that’s tax-aware, realistic with current cash flow, flexible enough for surprises, and sustainable for more than three months. That’s why the right answer is almost always a split, not an all-in bet on a single goal.

Checklist

Capture the employer match before anything else.
Fund the RESP at least to the $500/yr grant level.
Decide whether RRSP or TFSA is the next best dollar for your bracket.
Compare extra mortgage payments against expected after-tax investment returns.
Keep the TFSA available for medium-term and emergency flexibility.
Re-sequence whenever daycare, school, or income changes materially.