YES! I want to reduce taxes and avoid the OAS clawback even with a large RRSP.
---Note this is the answer if the OP was still 63... It really makes no difference if you are already 71, other than to note that you should move your bank before creating your RRIF to make it easier --
I plan to defer my CPP and OAS until after age 71, and draw down my RRSP between retirement and age 71 a bit faster, but keeping my income under $90k/yr during this time. (This being a sweet spot for my tax rates).
While I do this, I am not subjected to minimum withdrawals and the RRSP accounts are a bit more flexible to switch to other banks, compared to a RRIF. Technically you can switch your RRSP to a RRIF now, and do the same thing, but RRIFS are a bit less mobile between banks due to the extra bank accounting paperwork for transfers.
This keeps my lifetime income taxes lower overall, but I have the same income to spend....in later years, I get more CPP / OAS but withdraw less from the (now smaller) RRIF for the same total income which is planned to remain under $79k/yr. after age 71. If I need more $$'s then I would have created larger non-registered or TFSA investments before age 71.
The RRIF minimums ramp up as you age, and can trigger OAS clawback if I live a long time (over age 88), and have a high RRIF account size with very high minimum withdrawals. (e.g., If I don't deflate the RRIF earlier)
example - age 88, RRIF value is $700k = $70k/yr income, minimum, going up each year. This is in the zone of large OAS clawbacks when combined with other income streams (CPP, other interest).
It is a balancing act of taxes and income before and after OAS payouts.
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The other advantage is that if you die with a large RRIF, and no spouse, you pay taxes at the highest marginal tax rate (51%?) on the RRIF or RRSP amounts over $215k on your final return. It's a hidden estate tax. That could mean up to 25% of your RRIF will go to taxes that could have gone to your heirs.
Another reason to deflate your RRSP / RRIF earlier in retirement and put the money into TFSA / Non registered accounts.