Publication 505
taxmap/pubs/p505-004.htm#en_us_publink10007280Sick pay is a payment to you to replace your regular wages while
you are temporarily absent from work due to sickness or personal injury. To
qualify as sick pay, it must be paid under a plan to which your employer is a
party.
If you receive sick pay from your employer or an agent of your
employer, income tax must be withheld. An agent who does not pay regular wages
to you may choose to withhold income tax at a flat rate.
However, if you receive sick pay from a third party who is not
acting as an agent of your employer, income tax will be withheld only if you
choose to have it withheld. See
Form W-4S below.
If you receive payments under a plan in which your employer does
not participate (such as an accident or health plan where you paid all the
premiums), the payments are not sick pay and usually are not taxable.
taxmap/pubs/p505-004.htm#en_us_publink10007281If you receive sick pay under a collective bargaining agreement
between your union and your employer, the agreement may determine the amount of
income tax withholding. See your union representative or your employer for more
information.
taxmap/pubs/p505-004.htm#en_us_publink10007282If you choose to have income tax withheld from sick pay paid
by a third party, such as an insurance company, you must fill out Form W-4S. Its
instructions contain a worksheet you can use to figure the amount you want
withheld. They also explain restrictions that may apply.
Give the completed form to the payer of your sick pay. The payer
must withhold according to your directions on the form.
Form W-4S remains in effect until you change or cancel it, or
stop receiving payments. You can change your withholding by giving a new Form
W-4S or a written notice to the payer of your sick pay.
taxmap/pubs/p505-004.htm#en_us_publink10007283
If you do not request withholding on Form W-4S, or if you do not have enough tax
withheld, you may have to pay estimated tax. If you do not pay enough tax,
either through estimated tax or withholding, or a combination of both, you may
have to pay a penalty. See chapters 2 and 4.