[relpar]

Playing 2/1 North makes an opening bid of 1♠. South, holding ♠KJ9, ♥K632,♦ J84, ♣ KT9, responds with a forcing 1NT. North now rebids 2NT, showing a balanced 18-19 points. What rebid should South make? 4♠? 3NT?

[nullve]

MPs: 3N (not even close)
IMPs: 4♠ (meh)

[DavidKok]

I'd bid 3NT at imps too. Either way you have a 3♠ bid instead of 4♠. The only hands with support that start with a forcing 1NT are the limit raises, so this paints an accurate picture of your hand (and regardless I'd argue 2NT is GF).

[helene_t]

DavidKok, on 2021-April-11, 03:01, said:

Either way you have a 3♠ bid instead of 4♠. The only hands with support that start with a forcing 1NT are the limit raises, so this paints an accurate picture of your hand (and regardless I'd argue 2NT is GF).

This is far from universal. It is quite common to play the immediate raise as something like 7-9, so the raise via 1NT can be 4-6 or 10-11.

Best is of course to play transfers, then you can bid 3♥ followed by 3NT which should show this hand.

[mycroft]

If you have the agreement, basically universal in North America, that the only non-forcing call over 2NT 18-19 rebid is "pass", 3♠ is absolutely forcing so you make it (and not 4♠).

I can see at MPs with two flat hands and excessive HCP bidding 3NT and trying to make the same tricks. Partner might have a "3NT choice of games" call after 3♠ (my partners and I don't, but many do); bidding 3♠ doesn't preclude 3NT.