Do you sometimes open 1NT with balanced hand an 18 hcps?

[Kelly]

Even though my partnership aggreement is for 1NT to mean 15-17 pts, I will sometimes open 1NT with a balanced hand and 18 high card pts.

Sometimes we miss a game because pd has 7 pts and if he knew I had 18 we would be in game.

But sometimes itworks better because it gives pd a better idea of the strength of my hand.

Thoughts?

[jabierpastor]

Really 1NT opening goes form 15 to 18 HCP, but we have to consider some adjustements now:
With 18 HCP if you have equal or more Q,s and J,s than A,s and K,s, assune you have just 17 HCP, in other case assume you have 19 HCP.
The same happens when you have 15 HCP, with equal or more Q,s and J,s then A,s and K,s you account for 14 HCP, in other cqase for 16 HCP.