He was Chief Butler of England for almost thirty years, first appointed by Richard II, and on 20 March 1399 received a pension of twenty marks a year in exchange for offices granted him by the Duke, paying at the same time five marks for the confirmation of two annuities of charges on the Duchy of Lancaster and also granted by the Duke. These annuities were confirmed to him by Henry IV, who appointed him constable of Wallingford Castle, and steward of the honours of Wallingford and St. Valery and of the Chiltern Hundreds. About the same time he succeeded Geoffrey Chaucer as forester of North Petherton Park, Somerset. On 5 November 1402, he received a grant of the chief butlership for life. Chaucer served as High Sheriff of Berkshire and Oxfordshire during 1400 and 1403 and as High Sheriff of Hampshire in 1413. He attended fifteen parliaments as knight of the shire for Oxfordshire and was Speaker of the House five times, a feat not surpassed until the 18th century. He was chosen speaker in the parliament that met at Gloucester in 1407, and on 9 November reminded the king that the accounts of the expenditure of the last subsidy had not been rendered. The chancellor interrupted him, declaring that they were not ready, and that for the future the lords would not promise them. He was chosen again in 1410 and in 1411, when, on making his 'protestation' and claiming the usual permission of free speech, he was answered by the king that he might speak as other speakers had done, but that no novelties would be allowed. He asked for a day's grace, and then made an apology. He was again chosen in 1414. On 23 February 1411 the queen gave him the manor of Woodstock and other estates during her life, and on 15 March the king assigned them to him after her death. In 1414 he also received a commission, in which he is called domicellus, to treat about the marriage of Henry V, and to take the homage of the Duke of Burgundy. A year later he served with the king in France, bringing into the field 12 men-at-arms and 37 archers. He was not present at the Battle of Agincourt, being sent back to England ill after the siege of Harfluer. It is unknown if he was really sick, or used it as an excuse to return to England. His retinue did march on to Agincourt. In 1417, he was employed to treat for peace with France. On the accession of Henry VI he appears to have been superseded in the chief butlership, and to have regained it shortly afterwards. In January 1424, he was appointed a member of the council, and the next year was one of the commissioners to decide a dispute between the Earl Marshal and the Earl of Warwick about precedence. In 1430–1431, he was appointed one of the executors of the will of the Duchess of York, and was by then very wealthy. Thomas Chaucer died at Ewelme Palace in the village of Ewelme, Oxfordshire on 18 November 1434 and is buried in St Mary's church in the village.