I guess only. If his RA is too low, he will remain under the old scheme. And most probably, his monthly payout will be the same as his cohort who have the min sum or FRS. But his payout will be much shortened instead of the normal 20 years under the old scheme.
Your topping up of 7k only is unlikely to increase his monthly payout but will lengthen his payout period.
To expand on Henry’s point, I assume the $7,000 figure was chosen for tax relief reasons.
However, that’s not the tax relief limit, or at least it might not be. Let’s suppose for example that your father has two other children (i.e. you have two siblings) with taxable income. They can each top up his Retirement Account and also collect $7,000 each in tax relief. So that’s $21,000/year (now if not already done for 2018, and every January thereafter), all enjoying tax relief.
OK, what if they don’t want to help out your dad but you do? No problem. Let’s suppose your siblings are both solidly in the 7% tax bracket, meaning that with a $7,000 top-up they’d each save $490 in taxes. So you hand them each $6,600 (let’s suppose) and make sure that they immediately top up your father’s RA by $7,000 each. They each get back $490 of that (tax savings next year), so they come out $90 ahead, your father comes out $7,000 ahead ($14,000 total), and you enjoy most of the tax savings ($400) since you paid for the top-ups, after all. And yes, families really do this. Just search for anybody/everybody who pays income tax who can qualify for tax relief (because your father is a tax relief qualified RA recipient to that person), and work it out. This is all perfectly legal (there’s no gift tax in Singapore) and even encouraged.
What else? Well, tax relief is only a tax relief limit. You and others are perfectly free to exceed the annual tax relief limit. The only top-up limit is when your father’s RA reaches the Enhanced Retirement Sum, which is a couple hundred thousand dollars away. (Right now, as I write this, each qualified person can get $14,000 in tax relief: $7,000 before the end of this year — I’d do it no later than December 26 to allow sufficient time for crediting — and $7,000 in January. If there are 3 qualified individuals available who can all do this — two siblings, for example — that’s $42,000 in top-ups with tax relief over the course of the next couple months.)
What else? If he has Ordinary Account funds then he can transfer those into his Retirement Account.
What else? He can defer payouts to as late as age 70.
What else? The HDB Lease Buyback Scheme may be available to him. Or renting out a room in his flat.
What else? If he has a spouse/partner who is a CPF member, don’t forget about her/him. Look for tax relief opportunities in that person, too, and also try to win some more bonus interest that way.