Is "up to" inclusive or exclusive?

The phrase up to is used to sort things into two groups based on their relationship to a criterion. The difficulty arises when the criterion to which up to refers consists of something that has a duration or value in itself, different from the values on either side of it.

Consider examples in which the criterion has no such distinct value

He was happy up to the moment he died.

Up to takeoff, the rocket is tethered to the launch pad.

Generally people consider the moment of death to have no duration. Dead or not-dead. Before death, happy; after death, not (or not determinable). The rocket is attached or not attached.

When the criterion has its own point on the scale, the use of up to becomes ambiguous (unless further qualified)

We will give dispensations for people earning up to $1000.

They are accepting applications up to July 1.

People who are up to 4 foot 6 inches tall are banned from the roller coaster.

What about people who earn exactly $1000? Those who apply on July 1? The 4 foot 6 inch daredevil?

As @Janus Bahs Jacquet suggests, the means of eliminating the ambiguity is to indicate whether the criterion value is included or excluded from the partition.

We will give dispensations for people earning up to and including $1000.

They are accepting applications up to, but not including, July 1.

People who are up to and including 4 foot 6 inches tall are banned from the roller coaster.

An alternative is to use under or over, before and after (or beyond)

We will give dispensations for people earning under $1001. [Note the change in amount]

They are accepting applications before July 1.

People who are under 4 foot 7 inches tall are banned from the roller coaster. [Again a change in value; this assumes most people report height in full inches].

The term until shares the same ambiguities with up to.

People do use the term in both ways (rightly or wrongly), so it is best to examine the context, to help you decide what is meant.

However, without additional information from the context, I would say that the correct meaning is up to but not including.

To express inclusion of the upper boundary, you can use up through instead of up to.

(And I agree with others that there are less ambiguous ways to express ranges and inclusion/exclusion of their limits.)

Up to, in itself, is open to interpretation on this point.

Often the writer's intent can be worked out from the context, and that is true of your case, because the second clause tells you that things are different for later visits.

To see this one can compare it to the following:

The study was carried out up to visit 11 under the name of X1. From visit 12 onwards, visits were carried out under a different name, X2.

Both versions make sense, but differ on the question of including visit 11.

They both also share the unfortunate feature that you need to read the second clause in order to fully understand the first. This is not good practice, especially in technical writing.

When precision is important it is usually better not to rely on up to.

In your case, it would be better to put up to and including, which would make the meaning of the first clause precise without reference to the second. There are also other ways of making the point more clearly, including that given by @medica in a comment.

I found a verse in the Bible (KJV) with up to

Consider 2 Corinthians 12:2,

I knew a man in Christ above fourteen years ago...such an one caught up to the third heaven

It clearly indicates that up to is exclusive rather than inclusive, because apostle Paul was caught up, but should have never been in the third heaven, no nobody did except the Lord Jesus Christ.