Companies don't offer any advice on filling out a W4 because they may not know the employee's circumstances.

Here is how I advise my clients:

If you are single you always claim S-0.

If you are married, the spouse with the higher salary claims M-0 when there are no dependents and M-X

for the number of dependents. The spouse with the lower salary always claims married at S-0 rate.

If there is a house involved then further calculation is done to determine further deductions to claim.

Follow this rule and the taxpayer will not owe at the end of the year.