Master of coin
Duties of the master of coin include keeping account of the receipts and expenditures from the royal treasury, receiving reports from royal officials, supervising the collection of taxes and custom duties, borrowing money, managing the royal treasury and supervising the three royal mints. The master of coin oversees a large number of offices and positions in the royal bureaucracy including the four Keepers of the Keys, the King's Counter, the King's Scales, the officers in charge of mints, harbormasters, tax farmers, customs sergeants, wool factors, toll collectors, pursers and wine factors.
During the War of Conquest Crispian Celtigar served Aegon I Targaryen as the first master of coin. Nearly two centuries later, even though Elaena Targaryen's husband sat on the king's small council as master of coin, it was widely known that she was the one performing the duties.
List of Known Masters of Coin
- Lord Crispian Celtigar, served under Aegon I Targaryen.
- Lord Alton Butterwell, served under Maegor I Targaryen.
- Lord Edwell Celtigar during the regency of Jaehaerys I Targaryen.
- Rego Draz of Pentos during the early reign of Jaehaerys I Targaryen
- Lord Martyn Tyrell, in the reign of Jaehaerys I Targaryen, though unofficially the duties were performed by his wife, Lady Florence Fossoway. 
- Lord Lyman Beesbury, served in the late reign of Jaehaerys I Targaryen and then his grandson Viserys I Targaryen.
- Prince Daemon Targaryen, served under his brother Viserys I Targaryen before being removed and later made master of laws.
- Ser Tyland Lannister, served Aegon II Targaryen and the Greens during the Dance of the Dragons.
- Lord Bartimos Celtigar, served Queen Rhaenyra Targaryen and the Blacks during the Dance of the Dragons.
- Isembard Arryn during the regency of Aegon III.
- Lord Ronnel Penrose, served under Daeron II Targaryen.
- Lord Ambrose Butterwell, served Daeron II and Aerys I Targaryen.
- Lord Qarlton Chelsted, served Aerys II Targaryen, later made Hand of the King.
- Lord Petyr Baelish, appointed during the reign of Robert Baratheon; continued to serve under his successor Joffrey Baratheon.
- Tyrion Lannister, appointed when Littlefinger left to court Lysa Tully.
- Lord Gyles Rosby - Lord Treasurer. Appointed after Tyrion's trial for Joffrey's murder.
- Ser Harys Swyft - Lord Treasurer and master of coin. Demoted from Hand of the King to replace Lord Rosby after his death.
A Game of Thrones
A Clash of Kings
A Storm of Swords
When Baelish goes to the Eyrie to court Lysa Arryn, Tyrion Lannister is named as his replacement, charged with funding the royal wedding. Tyrion is blamed for the so-called dwarf's pennies. After Tyrion is imprisoned for the death of Joffrey, Tywin calls for Garth Tyrell to fill the post.
A Feast for Crows
After the death of Tywin Lannister, Queen Regent Cersei Lannister renames the office lord treasurer, a style used in the Free Cities,, as well as in Sunspear. When she hears Garth Tyrell will soon fill the seat, she appoints Lord Gyles Rosby to take the seat. When Lord Rosby dies, Harys Swyft is his replacement.
A Dance with Dragons
The Winds of Winter
Harys Swyft has traveled to Braavos to treat with the Iron Bank in person.
The master of coin must be frugal.
Within three years of his coming to court, he was master of coin and a member of the small council, and today the crown’s revenues were ten times what they had been under his beleaguered predecessor… though the crown’s debts had grown vast as well.
- A Clash of Kings, Chapter 17, Tyrion IV.
- Three Maidens in the Tower (June 27, 2006) So Spake Martin
- Fire & Blood, A Surfeit of Rulers.
- Fire & Blood, The Long Reign - Jaehaerys and Alysanne: Policy, Progeny, and Pain.
- The Princess and the Queen.
- The Rogue Prince.
- Fire & Blood, The Dying of the Dragons - Rhaenyra Triumphant.
- Fire & Blood, Under the Regents - Lysene Spring and the End of Regency.
- A Storm of Swords, Chapter 38, Tyrion V.
- A Feast for Crows, Chapter 17, Cersei IV.
- A Feast for Crows, Appendix
- A Game of Thrones, Chapter 20, Eddard IV.
- A Game of Thrones, Chapter 58, Eddard XV.