It is hard for him to go to work so he signs in as present on the days when he is absent

Firstly: 

We ask Allaah to reward you with good for your desire to
treat your wife’s mother kindly and to bring your wife close to her family,
and for the travelling, moving and giving up work that you are putting up
with for this purpose. 

Secondly: 

What you have done – signing for the days when you are absent
from work – is undoubtedly a haraam action, because it involves lying and
consuming people’s wealth unlawfully. Allaah says (interpretation of the
meaning): 

“O you who believe! Eat not up your property among
yourselves unjustly”

[al-Nisa’ 4:29]

And the Prophet (peace and blessings of Allaah be upon
him) said: “Truthfulness leads to righteousness and righteousness leads to
Paradise. A man will keep speaking the truth and striving to speak the truth
until he will be recorded with Allaah as a siddeeq (speaker of the
truth). Lying leads to immorality and immorality leads to Hellfire. A man
will keep telling lies and striving to tell lies until he is recorded with
Allaah as a liar.” Narrated by al-Bukhaari, 5629; Muslim, 4719. 

Thirdly: 

The salary that you have taken in return for these days
should be given back to your workplace; it is not permissible for you to
keep it because it is haraam wealth. The Prophet (peace and blessings
of Allaah be upon him) said: “Every body that is nourished with haraam food,
the Fire is more fitting for it.” Narrated by al-Tabaraani from Abu Bakr;
classed as saheeh by al-Albaani in Saheeh al-Jaami, 4519. 

Al-Tirmidhi (614) narrated from the hadeeth of Ka’b ibn
‘Ajzah: “There is no flesh that grows from haraam food but the Fire is most
suited for it.” Classed as saheeh by al-Albaani in Saheeh al-Tirmidhi. 

You have no right to
give this money in charity, because wealth can only be given in charity when
its owner is unknown or it is too difficult to reach him. 

Fourthly: 

It is not permissible for you to carry on being absent from
work whilst signing in as present. You should look for a way out that will
not involve sin, or you should agree to take early retirement now, without
getting the incentive of the lump sum that you mentioned. Remember that that
which is with Allaah can only be attained by obeying Him, and that haraam
wealth erases blessings and will bring evil consqeuences in this world and
in the Hereafter. 

This advice was offered by Shaykh Ibn Baaz (may Allaah have
mercy on him) to the one who was careless about his attendance at work, and
was not honest in recording the times when he was present. He (may Allaah
have mercy on him) said: “It is a duty for every Muslim to fulfil his trusts
and to beware of cheating at work with regard to attendance and absence and
in all matters. What he must do is to record the time when he entered and
the time when he left, so that he will have discharged his duty. The boss
has to advise them sincerely and direct them to do that which is good, and
warn them against cheating. And Allaah is the Source of strength. End quote
from Majmoo’ Fataawa al-Shaykh Ibn Baaz, 19/356. 

We ask Allaah to guide us and you. 

And Allaah knows best.