+0
Hi,

I think I learned from a several (or just several?) grammar books that "ths" referring to dates are not to be recommended in formal writings, Is it true?

For example,

My birthday is in 15th.

The party is on July 5th.

If I was writing a formal (?) sentence, do we include the year when stating the date of birthday?

My birthday is July 15, 2005
Comments 
Yes, it is generally considered informal to write the date as (for example) "July 15th". If you're only putting it on a birthday invitation though, it should be okay to write it whichever way you prefer.
My birthday is in 15th.
Also, if you were going to write it this way it should say, "My birthday is on the 15th".
Believer
Hi,

I think I learned from a several (or just several?) grammar books that "ths" referring to dates are not to be recommended in formal writings, Is it true?

For example,

My birthday is in 15th.

The party is on July 5th.

If I was writing a formal (?) sentence, do we include the year when stating the date of birthday?

My birthday is July 15, 2005

I think I learned from a several...

I think I learned from several... ( no (a) here) It's right now.
do we use "th" after a date?