| Cover | Dec. 14, 2023 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Dec. 14, 2023 |
| Entity File Number | 814-00818 |
| Entity Registrant Name | PHENIXFIN CORPORATION |
| Entity Central Index Key | 0001490349 |
| Entity Tax Identification Number | 27-4576073 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 445 Park Avenue |
| Entity Address, Address Line Two | 10th Floor |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10022 |
| City Area Code | 212 |
| Local Phone Number | 859-0390 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock, par value $0.001 per share | |
| Title of 12(b) Security | Common Stock, par value $0.001 per share |
| Trading Symbol | PFX |
| Security Exchange Name | NASDAQ |
| 5.25% Notes due 2028 | |
| Title of 12(b) Security | 5.25% Notes due 2028 |
| Trading Symbol | PFXNZ |
| Security Exchange Name | NASDAQ |
