Short answer
In general you may keep wealth you earned and received before Islam, even from things Islam forbids such as interest or selling alcohol, because Islam wipes out what came before it. What you must give up is any interest or haram payment still owed to you, and anything taken by theft or fraud must go back to its owner.
Hanafi jurists hold that dealings a non-Muslim completed before Islam stand, and the convert keeps what he received, based on the verse 'he may have what is past'. Interest and haram payments not yet received are cancelled. Property taken by theft, fraud or force is not his and must be returned where possible, or given in charity for the owner if they cannot be found. After Islam he may not sell alcohol or pork he still owns.
The four schools agree on this.
Explanation
When the Quran forbade interest, it said that whoever stops after the warning may have what is past, and told believers to give up only what remains due. In his farewell sermon the Prophet ﷺ cancelled the interest owed from before Islam while leaving people their capital. So a new Muslim is not asked to empty their bank account.
- Usually yours to keep: salary from a job Islam forbids, profit from selling alcohol, and interest already paid to you before Islam.
- Give up from now: interest still due to you, payments still owed under a haram contract, and the haram job or business itself, as soon as you reasonably can.
- Return: anything stolen or taken by fraud. Debts you owe people remain debts.
- At home: alcohol and pork you own should be poured away or thrown out, not sold or given away.
Ongoing contracts need care. Interest-bearing mortgages, loans, savings accounts and pension funds started before Islam each have their own answer, and leaving them can have real costs. Do not rush into a decision that harms your family; ask a qualified mufti with the details. Meanwhile, move what you can into halal options and give away any interest that arrives after your shahada.
Leaving a haram job can be the hardest step. Look for halal work with intention and patience, and trust that whoever leaves something for Allah is given something better. See what is riba and are past sins forgiven.
Ask a mufti about your own case. This answer explains the general ruling. When the details of your situation matter, as they do here, ask a qualified mufti and give them the full facts. Where to ask a scholar.
The evidence
Quran, Surah Al-Baqara 2:275
ٱلَّذِينَ يَأْكُلُونَ ٱلرِّبَوٰا۟ لَا يَقُومُونَ إِلَّا كَمَا يَقُومُ ٱلَّذِى يَتَخَبَّطُهُ ٱلشَّيْطَٰنُ مِنَ ٱلْمَسِّ ۚ ذَٰلِكَ بِأَنَّهُمْ قَالُوٓا۟ إِنَّمَا ٱلْبَيْعُ مِثْلُ ٱلرِّبَوٰا۟ ۗ وَأَحَلَّ ٱللَّهُ ٱلْبَيْعَ وَحَرَّمَ ٱلرِّبَوٰا۟ ۚ فَمَن جَآءَهُۥ مَوْعِظَةٌۭ مِّن رَّبِّهِۦ فَٱنتَهَىٰ فَلَهُۥ مَا سَلَفَ وَأَمْرُهُۥٓ إِلَى ٱللَّهِ ۖ وَمَنْ عَادَ فَأُو۟لَٰٓئِكَ أَصْحَٰبُ ٱلنَّارِ ۖ هُمْ فِيهَا خَٰلِدُونَ ﴿٢٧٥﴾
Those who consume interest cannot stand [on the Day of Resurrection] except as one stands who is being beaten by Satan into insanity. That is because they say, "Trade is [just] like interest." But Allah has permitted trade and has forbidden interest. So whoever has received an admonition from his Lord and desists may have what is past, and his affair rests with Allah. But whoever returns to [dealing in interest or usury] - those are the companions of the Fire; they will abide eternally therein.
What was received before the prohibition is kept.
Quran, Surah Al-Baqara 2:279
فَإِن لَّمْ تَفْعَلُوا۟ فَأْذَنُوا۟ بِحَرْبٍۢ مِّنَ ٱللَّهِ وَرَسُولِهِۦ ۖ وَإِن تُبْتُمْ فَلَكُمْ رُءُوسُ أَمْوَٰلِكُمْ لَا تَظْلِمُونَ وَلَا تُظْلَمُونَ ﴿٢٧٩﴾
And if you do not, then be informed of a war [against you] from Allah and His Messenger. But if you repent, you may have your principal - [thus] you do no wrong, nor are you wronged.
Interest still owed is given up while the capital remains.
Quran, Surah Al-Anfaal 8:38
قُل لِّلَّذِينَ كَفَرُوٓا۟ إِن يَنتَهُوا۟ يُغْفَرْ لَهُم مَّا قَدْ سَلَفَ وَإِن يَعُودُوا۟ فَقَدْ مَضَتْ سُنَّتُ ٱلْأَوَّلِينَ ﴿٣٨﴾
Say to those who have disbelieved [that] if they cease, what has previously occurred will be forgiven for them. But if they return [to hostility] - then the precedent of the former [rebellious] peoples has already taken place.
What happened before Islam is forgiven.
Sahih Muslim 121
Sahih... أن الإسلام يهدم ما كان قبله ...
"Islam wipes out what came before it."
Dealings before Islam are not held against the convert.
Sahih Muslim 1218
Sahih... ربا الجاهلية موضوع ...
"The interest of the time before Islam is cancelled."
Outstanding interest from before Islam is dropped.
Where the ruling is recorded
- Bada'i al-Sana'i, Kitab al-Buyu', the discussion of riba. Contracts completed before Islam stand, and what remains unpaid of riba is cancelled.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Buyu', Bab al-Bay' al-Fasid, discussion of unlawful wealth. Wealth taken unlawfully is returned to its owner or given in charity if the owner is unknown.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.